| Message ID | 20240119175730.15484-4-gregory.price@memverge.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/mempolicy: weighted interleave mempolicy and sysfs extension | expand |
Gregory Price <gourry.memverge@gmail.com> writes: > When a system has multiple NUMA nodes and it becomes bandwidth hungry, > using the current MPOL_INTERLEAVE could be an wise option. > > However, if those NUMA nodes consist of different types of memory such > as socket-attached DRAM and CXL/PCIe attached DRAM, the round-robin > based interleave policy does not optimally distribute data to make use > of their different bandwidth characteristics. > > Instead, interleave is more effective when the allocation policy follows > each NUMA nodes' bandwidth weight rather than a simple 1:1 distribution. > > This patch introduces a new memory policy, MPOL_WEIGHTED_INTERLEAVE, > enabling weighted interleave between NUMA nodes. Weighted interleave > allows for proportional distribution of memory across multiple numa > nodes, preferably apportioned to match the bandwidth of each node. > > For example, if a system has 1 CPU node (0), and 2 memory nodes (0,1), > with bandwidth of (100GB/s, 50GB/s) respectively, the appropriate > weight distribution is (2:1). > > Weights for each node can be assigned via the new sysfs extension: > /sys/kernel/mm/mempolicy/weighted_interleave/ > > For now, the default value of all nodes will be `1`, which matches > the behavior of standard 1:1 round-robin interleave. An extension > will be added in the future to allow default values to be registered > at kernel and device bringup time. > > The policy allocates a number of pages equal to the set weights. For > example, if the weights are (2,1), then 2 pages will be allocated on > node0 for every 1 page allocated on node1. > > The new flag MPOL_WEIGHTED_INTERLEAVE can be used in set_mempolicy(2) > and mbind(2). > > There are 3 integration points: > > weighted_interleave_nodes: > Counts the number of allocations as they occur, and applies the > weight for the current node. When the weight reaches 0, switch > to the next node. > > weighted_interleave_nid: > Gets the total weight of the nodemask as well as each individual > node weight, then calculates the node based on the given index. > > bulk_array_weighted_interleave: > Gets the total weight of the nodemask as well as each individual > node weight, then calculates the number of "interleave rounds" as > well as any delta ("partial round"). Calculates the number of > pages for each node and allocates them. > > If a node was scheduled for interleave via interleave_nodes, the > current weight (pol->cur_weight) will be allocated first, before > the remaining bulk calculation is done. > > One piece of complexity is the interaction between a recent refactor > which split the logic to acquire the "ilx" (interleave index) of an > allocation and the actually application of the interleave. The > calculation of the `interleave index` is done by `get_vma_policy()`, > while the actual selection of the node will be later appliex by the > relevant weighted_interleave function. > > Suggested-by: Hasan Al Maruf <Hasan.Maruf@amd.com> > Signed-off-by: Gregory Price <gregory.price@memverge.com> > Co-developed-by: Rakie Kim <rakie.kim@sk.com> > Signed-off-by: Rakie Kim <rakie.kim@sk.com> > Co-developed-by: Honggyu Kim <honggyu.kim@sk.com> > Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> > Co-developed-by: Hyeongtak Ji <hyeongtak.ji@sk.com> > Signed-off-by: Hyeongtak Ji <hyeongtak.ji@sk.com> > Co-developed-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> > Signed-off-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> > Co-developed-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> > Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> > --- > .../admin-guide/mm/numa_memory_policy.rst | 9 + > include/linux/mempolicy.h | 5 + > include/uapi/linux/mempolicy.h | 1 + > mm/mempolicy.c | 234 +++++++++++++++++- > 4 files changed, 246 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst > index eca38fa81e0f..a70f20ce1ffb 100644 > --- a/Documentation/admin-guide/mm/numa_memory_policy.rst > +++ b/Documentation/admin-guide/mm/numa_memory_policy.rst > @@ -250,6 +250,15 @@ MPOL_PREFERRED_MANY > can fall back to all existing numa nodes. This is effectively > MPOL_PREFERRED allowed for a mask rather than a single node. > > +MPOL_WEIGHTED_INTERLEAVE > + This mode operates the same as MPOL_INTERLEAVE, except that > + interleaving behavior is executed based on weights set in > + /sys/kernel/mm/mempolicy/weighted_interleave/ > + > + Weighted interleave allocates pages on nodes according to a > + weight. For example if nodes [0,1] are weighted [5,2], 5 pages > + will be allocated on node0 for every 2 pages allocated on node1. > + > NUMA memory policy supports the following optional mode flags: > > MPOL_F_STATIC_NODES > diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h > index 931b118336f4..c1a083eb0dd5 100644 > --- a/include/linux/mempolicy.h > +++ b/include/linux/mempolicy.h > @@ -54,6 +54,11 @@ struct mempolicy { > nodemask_t cpuset_mems_allowed; /* relative to these nodes */ > nodemask_t user_nodemask; /* nodemask passed by user */ > } w; > + > + /* Weighted interleave settings */ > + struct { > + u8 cur_weight; > + } wil; > }; > > /* > diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h > index a8963f7ef4c2..1f9bb10d1a47 100644 > --- a/include/uapi/linux/mempolicy.h > +++ b/include/uapi/linux/mempolicy.h > @@ -23,6 +23,7 @@ enum { > MPOL_INTERLEAVE, > MPOL_LOCAL, > MPOL_PREFERRED_MANY, > + MPOL_WEIGHTED_INTERLEAVE, > MPOL_MAX, /* always last member of enum */ > }; > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 427bddf115df..aa3b2389d3e0 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -19,6 +19,13 @@ > * for anonymous memory. For process policy an process counter > * is used. > * > + * weighted interleave > + * Allocate memory interleaved over a set of nodes based on > + * a set of weights (per-node), with normal fallback if it > + * fails. Otherwise operates the same as interleave. > + * Example: nodeset(0,1) & weights (2,1) - 2 pages allocated > + * on node 0 for every 1 page allocated on node 1. > + * > * bind Only allocate memory on a specific set of nodes, > * no fallback. > * FIXME: memory is allocated starting with the first node > @@ -313,6 +320,7 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, > policy->mode = mode; > policy->flags = flags; > policy->home_node = NUMA_NO_NODE; > + policy->wil.cur_weight = 0; > > return policy; > } > @@ -425,6 +433,10 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = { > .create = mpol_new_nodemask, > .rebind = mpol_rebind_preferred, > }, > + [MPOL_WEIGHTED_INTERLEAVE] = { > + .create = mpol_new_nodemask, > + .rebind = mpol_rebind_nodemask, > + }, > }; > > static bool migrate_folio_add(struct folio *folio, struct list_head *foliolist, > @@ -846,7 +858,8 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags, > > old = current->mempolicy; > current->mempolicy = new; > - if (new && new->mode == MPOL_INTERLEAVE) > + if (new && (new->mode == MPOL_INTERLEAVE || > + new->mode == MPOL_WEIGHTED_INTERLEAVE)) > current->il_prev = MAX_NUMNODES-1; > task_unlock(current); > mpol_put(old); > @@ -872,6 +885,7 @@ static void get_policy_nodemask(struct mempolicy *pol, nodemask_t *nodes) > case MPOL_INTERLEAVE: > case MPOL_PREFERRED: > case MPOL_PREFERRED_MANY: > + case MPOL_WEIGHTED_INTERLEAVE: > *nodes = pol->nodes; > break; > case MPOL_LOCAL: > @@ -956,6 +970,13 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask, > } else if (pol == current->mempolicy && > pol->mode == MPOL_INTERLEAVE) { > *policy = next_node_in(current->il_prev, pol->nodes); > + } else if (pol == current->mempolicy && > + (pol->mode == MPOL_WEIGHTED_INTERLEAVE)) { > + if (pol->wil.cur_weight) > + *policy = current->il_prev; > + else > + *policy = next_node_in(current->il_prev, > + pol->nodes); > } else { > err = -EINVAL; > goto out; > @@ -1785,7 +1806,8 @@ struct mempolicy *get_vma_policy(struct vm_area_struct *vma, > pol = __get_vma_policy(vma, addr, ilx); > if (!pol) > pol = get_task_policy(current); > - if (pol->mode == MPOL_INTERLEAVE) { > + if (pol->mode == MPOL_INTERLEAVE || > + pol->mode == MPOL_WEIGHTED_INTERLEAVE) { Should change the comments above get_vma_policy() definition too. > *ilx += vma->vm_pgoff >> order; > *ilx += (addr - vma->vm_start) >> (PAGE_SHIFT + order); > } > @@ -1835,6 +1857,28 @@ bool apply_policy_zone(struct mempolicy *policy, enum zone_type zone) > return zone >= dynamic_policy_zone; > } > > +static unsigned int weighted_interleave_nodes(struct mempolicy *policy) > +{ > + unsigned int next; > + struct task_struct *me = current; > + u8 __rcu *table; > + > + next = next_node_in(me->il_prev, policy->nodes); > + if (next == MAX_NUMNODES) > + return next; > + > + rcu_read_lock(); > + table = rcu_dereference(iw_table); > + if (!policy->wil.cur_weight) > + policy->wil.cur_weight = table ? table[next] : 1; > + rcu_read_unlock(); > + > + policy->wil.cur_weight--; > + if (!policy->wil.cur_weight) > + me->il_prev = next; > + return next; > +} > + > /* Do dynamic interleaving for a process */ > static unsigned int interleave_nodes(struct mempolicy *policy) > { > @@ -1869,6 +1913,9 @@ unsigned int mempolicy_slab_node(void) > case MPOL_INTERLEAVE: > return interleave_nodes(policy); > > + case MPOL_WEIGHTED_INTERLEAVE: > + return weighted_interleave_nodes(policy); > + > case MPOL_BIND: > case MPOL_PREFERRED_MANY: > { > @@ -1907,6 +1954,39 @@ static unsigned int read_once_policy_nodemask(struct mempolicy *pol, > return nodes_weight(*mask); > } > > +static unsigned int weighted_interleave_nid(struct mempolicy *pol, pgoff_t ilx) > +{ > + nodemask_t nodemask; > + unsigned int target, nr_nodes; > + u8 __rcu *table; > + unsigned int weight_total = 0; > + u8 weight; > + int nid; > + > + nr_nodes = read_once_policy_nodemask(pol, &nodemask); > + if (!nr_nodes) > + return numa_node_id(); > + > + rcu_read_lock(); > + table = rcu_dereference(iw_table); > + /* calculate the total weight */ > + for_each_node_mask(nid, nodemask) > + weight_total += table ? table[nid] : 1; > + > + /* Calculate the node offset based on totals */ > + target = ilx % weight_total; > + nid = first_node(nodemask); > + while (target) { > + weight = table ? table[nid] : 1; > + if (target < weight) > + break; > + target -= weight; > + nid = next_node_in(nid, nodemask); > + } > + rcu_read_unlock(); > + return nid; > +} > + > /* > * Do static interleaving for interleave index @ilx. Returns the ilx'th > * node in pol->nodes (starting from ilx=0), wrapping around if ilx > @@ -1967,6 +2047,11 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol, > *nid = (ilx == NO_INTERLEAVE_INDEX) ? > interleave_nodes(pol) : interleave_nid(pol, ilx); > break; > + case MPOL_WEIGHTED_INTERLEAVE: > + *nid = (ilx == NO_INTERLEAVE_INDEX) ? > + weighted_interleave_nodes(pol) : > + weighted_interleave_nid(pol, ilx); > + break; > } > > return nodemask; > @@ -2028,6 +2113,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask) > case MPOL_PREFERRED_MANY: > case MPOL_BIND: > case MPOL_INTERLEAVE: > + case MPOL_WEIGHTED_INTERLEAVE: > *mask = mempolicy->nodes; > break; > > @@ -2127,7 +2213,8 @@ struct page *alloc_pages_mpol(gfp_t gfp, unsigned int order, > * If the policy is interleave or does not allow the current > * node in its nodemask, we allocate the standard way. > */ > - if (pol->mode != MPOL_INTERLEAVE && > + if ((pol->mode != MPOL_INTERLEAVE && > + pol->mode != MPOL_WEIGHTED_INTERLEAVE) && > (!nodemask || node_isset(nid, *nodemask))) { > /* > * First, try to allocate THP only on local node, but > @@ -2263,6 +2350,135 @@ static unsigned long alloc_pages_bulk_array_interleave(gfp_t gfp, > return total_allocated; > } > > +static unsigned long alloc_pages_bulk_array_weighted_interleave(gfp_t gfp, > + struct mempolicy *pol, unsigned long nr_pages, > + struct page **page_array) > +{ > + struct task_struct *me = current; > + unsigned long total_allocated = 0; > + unsigned long nr_allocated; > + unsigned long rounds; > + unsigned long node_pages, delta; > + u8 weight, resume_weight; > + u8 __rcu *table; > + u8 *weights; > + unsigned int weight_total = 0; > + unsigned long rem_pages = nr_pages; > + nodemask_t nodes; > + int nnodes, node, weight_nodes, resume_node; > + int prev_node = NUMA_NO_NODE; It appears that we should initialize prev_node with me->il_prev? Details are as below. > + bool delta_depleted = false; > + int i; > + > + if (!nr_pages) > + return 0; > + > + nnodes = read_once_policy_nodemask(pol, &nodes); > + if (!nnodes) > + return 0; > + > + /* Continue allocating from most recent node and adjust the nr_pages */ > + if (pol->wil.cur_weight) { > + node = next_node_in(me->il_prev, nodes); > + node_pages = pol->wil.cur_weight; > + if (node_pages > rem_pages) > + node_pages = rem_pages; > + nr_allocated = __alloc_pages_bulk(gfp, node, NULL, node_pages, > + NULL, page_array); > + page_array += nr_allocated; > + total_allocated += nr_allocated; > + /* if that's all the pages, no need to interleave */ > + if (rem_pages <= pol->wil.cur_weight) { > + pol->wil.cur_weight -= rem_pages; If "pol->wil.cur_weight == 0" here, we need to change me->il_prev? > + return total_allocated; > + } > + /* Otherwise we adjust nr_pages down, and continue from there */ > + rem_pages -= pol->wil.cur_weight; > + pol->wil.cur_weight = 0; > + prev_node = node; > + } else { prev_node = me->il_prev; } > + > + /* fetch the weights for this operation and calculate total weight */ > + weights = kmalloc(nnodes, GFP_KERNEL); > + if (!weights) > + return total_allocated; > + > + rcu_read_lock(); > + table = rcu_dereference(iw_table); > + weight_nodes = 0; We can replace "weight_nodes" with "i" and use a "for" loop? > + while (weight_nodes < nnodes) { > + node = next_node_in(prev_node, nodes); IIUC, "node" will not change in the loop, so all "weight" below will be the same value. To keep it simple, I think we can just copy weights from the global iw_table and consider the default value? > + weight = table ? table[node] : 1; > + weights[weight_nodes++] = weight; > + weight_total += weight; > + } > + rcu_read_unlock(); > + > + /* > + * Now we can continue allocating from 0 instead of an offset > + * We calculate the number of rounds and any partial rounds so > + * that we minimize the number of calls to __alloc_pages_bulk > + * This requires us to track which node we should resume from. > + * > + * if (rounds > 0) and (delta == 0), resume_node will always be > + * the current me->il_prev > + * > + * if (delta > 0) and delta is depleted exactly on a node-weight > + * boundary, resume node will be the node last allocated from when > + * delta reached 0. > + * > + * if (delta > 0) and delta is not depleted on a node-weight boundary, > + * resume node will be the node prior to the node last allocated from. > + * > + * (rounds == 0) and (delta == 0) is not possible (earlier exit) > + */ > + rounds = rem_pages / weight_total; > + delta = rem_pages % weight_total; > + /* If no delta, we'll resume from current prev_node and first weight */ > + for (i = 0; i < nnodes; i++) { > + node = next_node_in(prev_node, nodes); > + weight = weights[i]; > + node_pages = weight * rounds; > + /* If a delta exists, add this node's portion of the delta */ > + if (delta >= weight) { > + node_pages += weight; > + delta -= weight; > + resume_node = node; > + resume_weight = i < (nnodes - 1) ? weights[i+1] : > + weights[0]; > + /* stop tracking iff (delta == weight) */ > + delta_depleted = !delta; > + } else if (delta) { /* <= weight */ The comment is unnecessary and wrong. > + /* if delta depleted, resume from this node */ > + node_pages += delta; > + delta = 0; > + resume_node = prev_node; > + resume_weight = weight - (node_pages % weight); > + delta_depleted = true; /* stop tracking */ > + } else if (!delta_depleted) { > + /* if there was no delta, track last allocated node */ > + resume_node = node; > + resume_weight = i < (nnodes - 1) ? weights[i+1] : > + weights[0]; > + } Can the above code be simplified as something like below? resume_node = prev_node; resume_weight = 0; for (...) { ... if (delta > weight) { node_pages += weight; delta -= weight; } else if (delta) { node_pages += delta; /* if delta depleted, resume from this node */ if (delta < weight) { resume_node = prev_node; resume_weight = weight - delta; } else { resume_node = node; } delta = 0; } ... } -- Best Regards, Huang, Ying > + /* node_pages can be 0 if an allocation fails and rounds == 0 */ > + if (!node_pages) > + break; > + nr_allocated = __alloc_pages_bulk(gfp, node, NULL, node_pages, > + NULL, page_array); > + page_array += nr_allocated; > + total_allocated += nr_allocated; > + if (total_allocated == nr_pages) > + break; > + prev_node = node; > + } > + /* resume allocating from the calculated node and weight */ > + me->il_prev = resume_node; > + pol->wil.cur_weight = resume_weight; > + kfree(weights); > + return total_allocated; > +} > + > static unsigned long alloc_pages_bulk_array_preferred_many(gfp_t gfp, int nid, > struct mempolicy *pol, unsigned long nr_pages, > struct page **page_array) > @@ -2303,6 +2519,10 @@ unsigned long alloc_pages_bulk_array_mempolicy(gfp_t gfp, > return alloc_pages_bulk_array_interleave(gfp, pol, > nr_pages, page_array); > > + if (pol->mode == MPOL_WEIGHTED_INTERLEAVE) > + return alloc_pages_bulk_array_weighted_interleave( > + gfp, pol, nr_pages, page_array); > + > if (pol->mode == MPOL_PREFERRED_MANY) > return alloc_pages_bulk_array_preferred_many(gfp, > numa_node_id(), pol, nr_pages, page_array); > @@ -2378,6 +2598,7 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b) > case MPOL_INTERLEAVE: > case MPOL_PREFERRED: > case MPOL_PREFERRED_MANY: > + case MPOL_WEIGHTED_INTERLEAVE: > return !!nodes_equal(a->nodes, b->nodes); > case MPOL_LOCAL: > return true; > @@ -2514,6 +2735,10 @@ int mpol_misplaced(struct folio *folio, struct vm_area_struct *vma, > polnid = interleave_nid(pol, ilx); > break; > > + case MPOL_WEIGHTED_INTERLEAVE: > + polnid = weighted_interleave_nid(pol, ilx); > + break; > + > case MPOL_PREFERRED: > if (node_isset(curnid, pol->nodes)) > goto out; > @@ -2888,6 +3113,7 @@ static const char * const policy_modes[] = > [MPOL_PREFERRED] = "prefer", > [MPOL_BIND] = "bind", > [MPOL_INTERLEAVE] = "interleave", > + [MPOL_WEIGHTED_INTERLEAVE] = "weighted interleave", > [MPOL_LOCAL] = "local", > [MPOL_PREFERRED_MANY] = "prefer (many)", > }; > @@ -2947,6 +3173,7 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) > } > break; > case MPOL_INTERLEAVE: > + case MPOL_WEIGHTED_INTERLEAVE: > /* > * Default to online nodes with memory if no nodelist > */ > @@ -3057,6 +3284,7 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) > case MPOL_PREFERRED_MANY: > case MPOL_BIND: > case MPOL_INTERLEAVE: > + case MPOL_WEIGHTED_INTERLEAVE: > nodes = pol->nodes; > break; > default:
On Tue, Jan 23, 2024 at 11:02:03AM +0800, Huang, Ying wrote: > Gregory Price <gourry.memverge@gmail.com> writes: > > > + int prev_node = NUMA_NO_NODE; > > It appears that we should initialize prev_node with me->il_prev? > Details are as below. > yeah good catch, was a rebase error from my tested code, where this is the case. patching now. > > + if (rem_pages <= pol->wil.cur_weight) { > > + pol->wil.cur_weight -= rem_pages; > > If "pol->wil.cur_weight == 0" here, we need to change me->il_prev? > you are right, and also need to fetch the next cur_weight. Seems I missed this specific case in my tests. (had this tested with a single node but not 2, so it looked right). Added to my test suite. > We can replace "weight_nodes" with "i" and use a "for" loop? > > > + while (weight_nodes < nnodes) { > > + node = next_node_in(prev_node, nodes); > > IIUC, "node" will not change in the loop, so all "weight" below will be > the same value. To keep it simple, I think we can just copy weights > from the global iw_table and consider the default value? > another rebase error here from my tested code, this should have been node = prev_node; while (...) node = next_node_in(node, nodes); I can change it to a for loop as suggested, but for more info on why I did it this way, see the chunk below > > + } else if (!delta_depleted) { > > + /* if there was no delta, track last allocated node */ > > + resume_node = node; > > + resume_weight = i < (nnodes - 1) ? weights[i+1] : > > + weights[0]; ^ this line acquires the weight of the *NEXT* node another chunk prior to this does the same thing. I suppose i can use next_node_in() instead and just copy the entire weigh array though, if that is preferable. > > + } > > Can the above code be simplified as something like below? > > resume_node = prev_node; > resume_weight = 0; > for (...) { > ... > if (delta > weight) { > node_pages += weight; > delta -= weight; > } else if (delta) { > node_pages += delta; > /* if delta depleted, resume from this node */ > if (delta < weight) { > resume_node = prev_node; > resume_weight = weight - delta; > } else { > resume_node = node; > } > delta = 0; > } > ... > } > I'll take another look at it, but this logic is annoying because of the corner case: me->il_prev can be NUMA_NO_NODE or an actual numa node. If it's NUMA_NO_NODE, then the logic you have above will say "the next node has no remaining weights assigned" and skip it on the next call to weighted_interleave_nid or weighted_interleave_nodes. This is incorrect - we want the weight of the first node to be resume_weight, which is what this chunk does: if (delta >= weight) { /* if delta == weight, get next node weight */ resume_weight = i < (nnodes - 1) ? weights[i+1] : weights[0]; else if (delta) { /* delta < weight */ /* there's a remaining weight, use the that for resume weight */ resume_weight = weight - (node_pages % weight); } else if (!delta_depleted) { /* there was never a delta, track the last node and get the weight * of the node AFTER that node, that's the resume weight */ resume_weight = i < (nnodes - 1) ? weights[i+1] : weights[0]; } If il_prev is an actual node, and delta == 0, we want to return with (il_prev = prev_node) but with the weight set to the weight of the first node we're about to allocate from. This is the reason for the annoying logic here: We have to come out of this loop with the actual node and the actual weight. I'll try to clean it up further and get my test suite to pass. ~Gregory
On Mon, Jan 22, 2024 at 11:54:34PM -0500, Gregory Price wrote: > > > > Can the above code be simplified as something like below? > > > > resume_node = prev_node; --- resume_weight = 0; +++ resume_weight = weights[node]; > > for (...) { > > ... > > } > > > > I'll take another look at it, but this logic is annoying because of the > corner case: me->il_prev can be NUMA_NO_NODE or an actual numa node. > After a quick look, as long as no one objects to (me->il_prev) remaining NUMA_NO_NODE while having a weight assigned to pol->wil.cur_weight, then this looks like it can be simplified as above. I don't think it's harmful, but i'll have to take a quick look at what happens on rebind to make sure we don't have a stale weight. ~Gregory
Gregory Price <gregory.price@memverge.com> writes: > On Tue, Jan 23, 2024 at 11:02:03AM +0800, Huang, Ying wrote: >> Gregory Price <gourry.memverge@gmail.com> writes: >> >> > + int prev_node = NUMA_NO_NODE; >> >> It appears that we should initialize prev_node with me->il_prev? >> Details are as below. >> > > yeah good catch, was a rebase error from my tested code, where this is > the case. patching now. > >> > + if (rem_pages <= pol->wil.cur_weight) { >> > + pol->wil.cur_weight -= rem_pages; >> >> If "pol->wil.cur_weight == 0" here, we need to change me->il_prev? >> > you are right, and also need to fetch the next cur_weight. Seems I > missed this specific case in my tests. (had this tested with a single > node but not 2, so it looked right). > > Added to my test suite. > >> We can replace "weight_nodes" with "i" and use a "for" loop? >> >> > + while (weight_nodes < nnodes) { >> > + node = next_node_in(prev_node, nodes); >> >> IIUC, "node" will not change in the loop, so all "weight" below will be >> the same value. To keep it simple, I think we can just copy weights >> from the global iw_table and consider the default value? >> > > another rebase error here from my tested code, this should have been > node = prev_node; > while (...) > node = next_node_in(node, nodes); > > I can change it to a for loop as suggested, but for more info on why I > did it this way, see the chunk below > >> > + } else if (!delta_depleted) { >> > + /* if there was no delta, track last allocated node */ >> > + resume_node = node; >> > + resume_weight = i < (nnodes - 1) ? weights[i+1] : >> > + weights[0]; > ^ this line acquires the weight of the *NEXT* node > another chunk prior to this does the same > thing. I suppose i can use next_node_in() > instead and just copy the entire weigh array > though, if that is preferable. Yes. I think copy the entire weight array make code logic simpler. -- Best Regards, Huang, Ying
Gregory Price <gregory.price@memverge.com> writes: > On Mon, Jan 22, 2024 at 11:54:34PM -0500, Gregory Price wrote: >> > >> > Can the above code be simplified as something like below? >> > >> > resume_node = prev_node; > --- resume_weight = 0; > +++ resume_weight = weights[node]; >> > for (...) { >> > ... >> > } >> > >> >> I'll take another look at it, but this logic is annoying because of the >> corner case: me->il_prev can be NUMA_NO_NODE or an actual numa node. >> > > After a quick look, as long as no one objects to (me->il_prev) remaining > NUMA_NO_NODE MAX_NUMNODES-1 ? > while having a weight assigned to pol->wil.cur_weight, I think that it is OK. And, IIUC, pol->wil.cur_weight can be 0, as in weighted_interleave_nodes(), if it's 0, it will be assigned to default weight for the node. > then > this looks like it can be simplified as above. > > I don't think it's harmful, but i'll have to take a quick look at what > happens on rebind to make sure we don't have a stale weight. Make sense. -- Best Regards, Huang, Ying
Gregory Price <gourry.memverge@gmail.com> writes: > When a system has multiple NUMA nodes and it becomes bandwidth hungry, > using the current MPOL_INTERLEAVE could be an wise option. > > However, if those NUMA nodes consist of different types of memory such > as socket-attached DRAM and CXL/PCIe attached DRAM, the round-robin > based interleave policy does not optimally distribute data to make use > of their different bandwidth characteristics. > > Instead, interleave is more effective when the allocation policy follows > each NUMA nodes' bandwidth weight rather than a simple 1:1 distribution. > > This patch introduces a new memory policy, MPOL_WEIGHTED_INTERLEAVE, > enabling weighted interleave between NUMA nodes. Weighted interleave > allows for proportional distribution of memory across multiple numa > nodes, preferably apportioned to match the bandwidth of each node. > > For example, if a system has 1 CPU node (0), and 2 memory nodes (0,1), > with bandwidth of (100GB/s, 50GB/s) respectively, the appropriate > weight distribution is (2:1). > > Weights for each node can be assigned via the new sysfs extension: > /sys/kernel/mm/mempolicy/weighted_interleave/ > > For now, the default value of all nodes will be `1`, which matches > the behavior of standard 1:1 round-robin interleave. An extension > will be added in the future to allow default values to be registered > at kernel and device bringup time. > > The policy allocates a number of pages equal to the set weights. For > example, if the weights are (2,1), then 2 pages will be allocated on > node0 for every 1 page allocated on node1. > > The new flag MPOL_WEIGHTED_INTERLEAVE can be used in set_mempolicy(2) > and mbind(2). > > There are 3 integration points: > > weighted_interleave_nodes: > Counts the number of allocations as they occur, and applies the > weight for the current node. When the weight reaches 0, switch > to the next node. > > weighted_interleave_nid: > Gets the total weight of the nodemask as well as each individual > node weight, then calculates the node based on the given index. > > bulk_array_weighted_interleave: > Gets the total weight of the nodemask as well as each individual > node weight, then calculates the number of "interleave rounds" as > well as any delta ("partial round"). Calculates the number of > pages for each node and allocates them. > > If a node was scheduled for interleave via interleave_nodes, the > current weight (pol->cur_weight) will be allocated first, before > the remaining bulk calculation is done. > > One piece of complexity is the interaction between a recent refactor > which split the logic to acquire the "ilx" (interleave index) of an > allocation and the actually application of the interleave. The > calculation of the `interleave index` is done by `get_vma_policy()`, > while the actual selection of the node will be later appliex by the > relevant weighted_interleave function. > > Suggested-by: Hasan Al Maruf <Hasan.Maruf@amd.com> > Signed-off-by: Gregory Price <gregory.price@memverge.com> > Co-developed-by: Rakie Kim <rakie.kim@sk.com> > Signed-off-by: Rakie Kim <rakie.kim@sk.com> > Co-developed-by: Honggyu Kim <honggyu.kim@sk.com> > Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> > Co-developed-by: Hyeongtak Ji <hyeongtak.ji@sk.com> > Signed-off-by: Hyeongtak Ji <hyeongtak.ji@sk.com> > Co-developed-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> > Signed-off-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> > Co-developed-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> > Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> > --- > .../admin-guide/mm/numa_memory_policy.rst | 9 + > include/linux/mempolicy.h | 5 + > include/uapi/linux/mempolicy.h | 1 + > mm/mempolicy.c | 234 +++++++++++++++++- > 4 files changed, 246 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst > index eca38fa81e0f..a70f20ce1ffb 100644 > --- a/Documentation/admin-guide/mm/numa_memory_policy.rst > +++ b/Documentation/admin-guide/mm/numa_memory_policy.rst > @@ -250,6 +250,15 @@ MPOL_PREFERRED_MANY > can fall back to all existing numa nodes. This is effectively > MPOL_PREFERRED allowed for a mask rather than a single node. > > +MPOL_WEIGHTED_INTERLEAVE > + This mode operates the same as MPOL_INTERLEAVE, except that > + interleaving behavior is executed based on weights set in > + /sys/kernel/mm/mempolicy/weighted_interleave/ > + > + Weighted interleave allocates pages on nodes according to a > + weight. For example if nodes [0,1] are weighted [5,2], 5 pages > + will be allocated on node0 for every 2 pages allocated on node1. > + > NUMA memory policy supports the following optional mode flags: > > MPOL_F_STATIC_NODES > diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h > index 931b118336f4..c1a083eb0dd5 100644 > --- a/include/linux/mempolicy.h > +++ b/include/linux/mempolicy.h > @@ -54,6 +54,11 @@ struct mempolicy { > nodemask_t cpuset_mems_allowed; /* relative to these nodes */ > nodemask_t user_nodemask; /* nodemask passed by user */ > } w; > + > + /* Weighted interleave settings */ > + struct { > + u8 cur_weight; > + } wil; > }; > > /* > diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h > index a8963f7ef4c2..1f9bb10d1a47 100644 > --- a/include/uapi/linux/mempolicy.h > +++ b/include/uapi/linux/mempolicy.h > @@ -23,6 +23,7 @@ enum { > MPOL_INTERLEAVE, > MPOL_LOCAL, > MPOL_PREFERRED_MANY, > + MPOL_WEIGHTED_INTERLEAVE, > MPOL_MAX, /* always last member of enum */ > }; > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 427bddf115df..aa3b2389d3e0 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -19,6 +19,13 @@ > * for anonymous memory. For process policy an process counter > * is used. > * > + * weighted interleave > + * Allocate memory interleaved over a set of nodes based on > + * a set of weights (per-node), with normal fallback if it > + * fails. Otherwise operates the same as interleave. > + * Example: nodeset(0,1) & weights (2,1) - 2 pages allocated > + * on node 0 for every 1 page allocated on node 1. > + * > * bind Only allocate memory on a specific set of nodes, > * no fallback. > * FIXME: memory is allocated starting with the first node > @@ -313,6 +320,7 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, > policy->mode = mode; > policy->flags = flags; > policy->home_node = NUMA_NO_NODE; > + policy->wil.cur_weight = 0; > > return policy; > } > @@ -425,6 +433,10 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = { > .create = mpol_new_nodemask, > .rebind = mpol_rebind_preferred, > }, > + [MPOL_WEIGHTED_INTERLEAVE] = { > + .create = mpol_new_nodemask, > + .rebind = mpol_rebind_nodemask, > + }, > }; > > static bool migrate_folio_add(struct folio *folio, struct list_head *foliolist, > @@ -846,7 +858,8 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags, > > old = current->mempolicy; > current->mempolicy = new; > - if (new && new->mode == MPOL_INTERLEAVE) > + if (new && (new->mode == MPOL_INTERLEAVE || > + new->mode == MPOL_WEIGHTED_INTERLEAVE)) > current->il_prev = MAX_NUMNODES-1; > task_unlock(current); > mpol_put(old); > @@ -872,6 +885,7 @@ static void get_policy_nodemask(struct mempolicy *pol, nodemask_t *nodes) > case MPOL_INTERLEAVE: > case MPOL_PREFERRED: > case MPOL_PREFERRED_MANY: > + case MPOL_WEIGHTED_INTERLEAVE: > *nodes = pol->nodes; > break; > case MPOL_LOCAL: > @@ -956,6 +970,13 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask, > } else if (pol == current->mempolicy && > pol->mode == MPOL_INTERLEAVE) { > *policy = next_node_in(current->il_prev, pol->nodes); > + } else if (pol == current->mempolicy && > + (pol->mode == MPOL_WEIGHTED_INTERLEAVE)) { > + if (pol->wil.cur_weight) > + *policy = current->il_prev; > + else > + *policy = next_node_in(current->il_prev, > + pol->nodes); Per my understanding, we should always use "*policy = next_node_in()" here, as in weighted_interleave_nodes(). > } else { > err = -EINVAL; > goto out; > @@ -1785,7 +1806,8 @@ struct mempolicy *get_vma_policy(struct vm_area_struct *vma, > pol = __get_vma_policy(vma, addr, ilx); > if (!pol) > pol = get_task_policy(current); > - if (pol->mode == MPOL_INTERLEAVE) { > + if (pol->mode == MPOL_INTERLEAVE || > + pol->mode == MPOL_WEIGHTED_INTERLEAVE) { > *ilx += vma->vm_pgoff >> order; > *ilx += (addr - vma->vm_start) >> (PAGE_SHIFT + order); > } > @@ -1835,6 +1857,28 @@ bool apply_policy_zone(struct mempolicy *policy, enum zone_type zone) > return zone >= dynamic_policy_zone; > } > > +static unsigned int weighted_interleave_nodes(struct mempolicy *policy) > +{ > + unsigned int next; > + struct task_struct *me = current; > + u8 __rcu *table; > + > + next = next_node_in(me->il_prev, policy->nodes); > + if (next == MAX_NUMNODES) > + return next; > + > + rcu_read_lock(); > + table = rcu_dereference(iw_table); > + if (!policy->wil.cur_weight) > + policy->wil.cur_weight = table ? table[next] : 1; > + rcu_read_unlock(); > + > + policy->wil.cur_weight--; > + if (!policy->wil.cur_weight) > + me->il_prev = next; > + return next; > +} > + [snip] -- Best Regards, Huang, Ying
On Tue, Jan 23, 2024 at 04:35:19PM +0800, Huang, Ying wrote: > Gregory Price <gregory.price@memverge.com> writes: > > > On Mon, Jan 22, 2024 at 11:54:34PM -0500, Gregory Price wrote: > >> > > >> > Can the above code be simplified as something like below? > >> > > >> > resume_node = prev_node; > > --- resume_weight = 0; > > +++ resume_weight = weights[node]; > >> > for (...) { > >> > ... > >> > } > >> > > >> > >> I'll take another look at it, but this logic is annoying because of the > >> corner case: me->il_prev can be NUMA_NO_NODE or an actual numa node. > >> > > > > After a quick look, as long as no one objects to (me->il_prev) remaining > > NUMA_NO_NODE > > MAX_NUMNODES-1 ? > When setting a new policy, the il_prev gets set to NUMA_NO_NODE. It's not harmful and is just (-1), which is functionally the same as (MAX_NUMNODES-1) for the purpose of iterating the nodemask with next_node_in(). So it's fine to set (resume_node = me->il_prev) as discussed. I have a cleaned up function I'll push when i fix up a few other spots. > > while having a weight assigned to pol->wil.cur_weight, > > I think that it is OK. > > And, IIUC, pol->wil.cur_weight can be 0, as in > weighted_interleave_nodes(), if it's 0, it will be assigned to default > weight for the node. > cur_weight is different than the global weights. cur_weight tells us how many pages are remaining to allocate for the current node. (cur_weight = 0) can happen in two scenarios: - initial setting of mempolicy (NUMA_NO_NODE w/ cur_weight=0) - weighted_interleave_nodes decrements it down to 0 Now that i'm looking at it - the second condition should not exist, and we can eliminate it. The logic in weighted_interleave_nodes is actually annoyingly unclear at the moment, so I'm going to re-factor it a bit to be more explicit. ~Gregory
Gregory Price <gregory.price@memverge.com> writes: > On Tue, Jan 23, 2024 at 04:35:19PM +0800, Huang, Ying wrote: >> Gregory Price <gregory.price@memverge.com> writes: >> >> > On Mon, Jan 22, 2024 at 11:54:34PM -0500, Gregory Price wrote: >> >> > >> >> > Can the above code be simplified as something like below? >> >> > >> >> > resume_node = prev_node; >> > --- resume_weight = 0; >> > +++ resume_weight = weights[node]; >> >> > for (...) { >> >> > ... >> >> > } >> >> > >> >> >> >> I'll take another look at it, but this logic is annoying because of the >> >> corner case: me->il_prev can be NUMA_NO_NODE or an actual numa node. >> >> >> > >> > After a quick look, as long as no one objects to (me->il_prev) remaining >> > NUMA_NO_NODE >> >> MAX_NUMNODES-1 ? >> > > When setting a new policy, the il_prev gets set to NUMA_NO_NODE. It's IIUC, it is set to MAX_NUMNODES-1 as below, @@ -846,7 +858,8 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags, old = current->mempolicy; current->mempolicy = new; - if (new && new->mode == MPOL_INTERLEAVE) + if (new && (new->mode == MPOL_INTERLEAVE || + new->mode == MPOL_WEIGHTED_INTERLEAVE)) current->il_prev = MAX_NUMNODES-1; task_unlock(current); mpol_put(old); I don't think we need to change this. > not harmful and is just (-1), which is functionally the same as > (MAX_NUMNODES-1) for the purpose of iterating the nodemask with > next_node_in(). So it's fine to set (resume_node = me->il_prev) > as discussed. > > I have a cleaned up function I'll push when i fix up a few other spots. > >> > while having a weight assigned to pol->wil.cur_weight, >> >> I think that it is OK. >> >> And, IIUC, pol->wil.cur_weight can be 0, as in >> weighted_interleave_nodes(), if it's 0, it will be assigned to default >> weight for the node. >> > > cur_weight is different than the global weights. cur_weight tells us > how many pages are remaining to allocate for the current node. > > (cur_weight = 0) can happen in two scenarios: > - initial setting of mempolicy (NUMA_NO_NODE w/ cur_weight=0) > - weighted_interleave_nodes decrements it down to 0 > > Now that i'm looking at it - the second condition should not exist, and > we can eliminate it. The logic in weighted_interleave_nodes is actually > annoyingly unclear at the moment, so I'm going to re-factor it a bit to > be more explicit. I am OK with either way. Just a reminder, the first condition may be true in alloc_pages_bulk_array_weighted_interleave() and perhaps some other places. -- Best Regards, Huang, Ying
On Wed, Jan 24, 2024 at 09:51:20AM +0800, Huang, Ying wrote: > Gregory Price <gregory.price@memverge.com> writes: > > + if (new && (new->mode == MPOL_INTERLEAVE || > + new->mode == MPOL_WEIGHTED_INTERLEAVE)) > current->il_prev = MAX_NUMNODES-1; > task_unlock(current); > mpol_put(old); > > I don't think we need to change this. > Ah you're right it's set to MAX_NUMNODES-1 here, but NUMA_NO_NODE can be passed in as an argument to alloc_pages_bulk_array_mempolicy, like here: vm_area_alloc_pages() if (IS_ENABLED(CONFIG_NUMA) && nid == NUMA_NO_NODE) nr = alloc_pages_bulk_array_mempolicy(bulk_gfp, nr_pages_request, pages + nr_allocated); > > (cur_weight = 0) can happen in two scenarios: > > - initial setting of mempolicy (NUMA_NO_NODE w/ cur_weight=0) > > - weighted_interleave_nodes decrements it down to 0 > > > > Now that i'm looking at it - the second condition should not exist, and > > we can eliminate it. The logic in weighted_interleave_nodes is actually > > annoyingly unclear at the moment, so I'm going to re-factor it a bit to > > be more explicit. > > I am OK with either way. Just a reminder, the first condition may be > true in alloc_pages_bulk_array_weighted_interleave() and perhaps some > other places. > Yeah, the bulk allocator handles it correctly, it's just a matter of clarity for weighted_interleave_nodes. What isn't necessarily handled correctly is the rebind code. Rebind due to a cgroup/mems_allowed change can cause a stale weight to be carried. Basically cur_weight is not cleared, but the node it applied to may no longer be the next node when next_node_in() is called. The race condition is 1) exceedingly rare, and 2) not necessarily harmful, just inaccurate. The worst case scenario is that a node receives up to 255 additional allocations once after a rebind (but more likely 10-20). I was considering forcing the interleave forward like this: @@ -356,6 +361,10 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes) tmp = *nodes; pol->nodes = tmp; + + /* Weighted interleave policies are forced forward to the next node */ + if (pol->mode & MPOL_WEIGHTED_INTERLEAVE) + pol->wil.cur_weight = 0; } But this creates 2 race conditions when we read cur_weight and nodemask in the allocator path. Example 1: 1) bulk allocator READ_ONCE(mask), READ_ONCE(cur_weight) 2) rebind changes nodemask and { cur_weight = 0; } 3) bulk allocator sets pol->wil.cur_weight In this scenario, resume_weight is stale coming out of bulk allocations if the resume_node has been removed from the node mask. Example 2: 1) rebind changes nodemask 2) bulk allocator READ_ONCE(mask), READ_ONCE(cur_weight) 3) rebind sets { cur_weight = 0; } In this scenario, cur_weight is stale going into bulk allocations. Neither of these can force a violation of mems_allowed, just a mis-application of a weight. I'll need to think on this a bit. We can either leave this as-is, meaning the first allocation after a rebind may apply the wrong weight to a node, or we can try to track the current-interleave-node and validate next_node_in(mask) == current-interleave-node before leaving the allocator path (this may also be just as racey). turns out concurrent counting is still hard :] ~Gregory
diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst index eca38fa81e0f..a70f20ce1ffb 100644 --- a/Documentation/admin-guide/mm/numa_memory_policy.rst +++ b/Documentation/admin-guide/mm/numa_memory_policy.rst @@ -250,6 +250,15 @@ MPOL_PREFERRED_MANY can fall back to all existing numa nodes. This is effectively MPOL_PREFERRED allowed for a mask rather than a single node. +MPOL_WEIGHTED_INTERLEAVE + This mode operates the same as MPOL_INTERLEAVE, except that + interleaving behavior is executed based on weights set in + /sys/kernel/mm/mempolicy/weighted_interleave/ + + Weighted interleave allocates pages on nodes according to a + weight. For example if nodes [0,1] are weighted [5,2], 5 pages + will be allocated on node0 for every 2 pages allocated on node1. + NUMA memory policy supports the following optional mode flags: MPOL_F_STATIC_NODES diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h index 931b118336f4..c1a083eb0dd5 100644 --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -54,6 +54,11 @@ struct mempolicy { nodemask_t cpuset_mems_allowed; /* relative to these nodes */ nodemask_t user_nodemask; /* nodemask passed by user */ } w; + + /* Weighted interleave settings */ + struct { + u8 cur_weight; + } wil; }; /* diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h index a8963f7ef4c2..1f9bb10d1a47 100644 --- a/include/uapi/linux/mempolicy.h +++ b/include/uapi/linux/mempolicy.h @@ -23,6 +23,7 @@ enum { MPOL_INTERLEAVE, MPOL_LOCAL, MPOL_PREFERRED_MANY, + MPOL_WEIGHTED_INTERLEAVE, MPOL_MAX, /* always last member of enum */ }; diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 427bddf115df..aa3b2389d3e0 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -19,6 +19,13 @@ * for anonymous memory. For process policy an process counter * is used. * + * weighted interleave + * Allocate memory interleaved over a set of nodes based on + * a set of weights (per-node), with normal fallback if it + * fails. Otherwise operates the same as interleave. + * Example: nodeset(0,1) & weights (2,1) - 2 pages allocated + * on node 0 for every 1 page allocated on node 1. + * * bind Only allocate memory on a specific set of nodes, * no fallback. * FIXME: memory is allocated starting with the first node @@ -313,6 +320,7 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, policy->mode = mode; policy->flags = flags; policy->home_node = NUMA_NO_NODE; + policy->wil.cur_weight = 0; return policy; } @@ -425,6 +433,10 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = { .create = mpol_new_nodemask, .rebind = mpol_rebind_preferred, }, + [MPOL_WEIGHTED_INTERLEAVE] = { + .create = mpol_new_nodemask, + .rebind = mpol_rebind_nodemask, + }, }; static bool migrate_folio_add(struct folio *folio, struct list_head *foliolist, @@ -846,7 +858,8 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags, old = current->mempolicy; current->mempolicy = new; - if (new && new->mode == MPOL_INTERLEAVE) + if (new && (new->mode == MPOL_INTERLEAVE || + new->mode == MPOL_WEIGHTED_INTERLEAVE)) current->il_prev = MAX_NUMNODES-1; task_unlock(current); mpol_put(old); @@ -872,6 +885,7 @@ static void get_policy_nodemask(struct mempolicy *pol, nodemask_t *nodes) case MPOL_INTERLEAVE: case MPOL_PREFERRED: case MPOL_PREFERRED_MANY: + case MPOL_WEIGHTED_INTERLEAVE: *nodes = pol->nodes; break; case MPOL_LOCAL: @@ -956,6 +970,13 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask, } else if (pol == current->mempolicy && pol->mode == MPOL_INTERLEAVE) { *policy = next_node_in(current->il_prev, pol->nodes); + } else if (pol == current->mempolicy && + (pol->mode == MPOL_WEIGHTED_INTERLEAVE)) { + if (pol->wil.cur_weight) + *policy = current->il_prev; + else + *policy = next_node_in(current->il_prev, + pol->nodes); } else { err = -EINVAL; goto out; @@ -1785,7 +1806,8 @@ struct mempolicy *get_vma_policy(struct vm_area_struct *vma, pol = __get_vma_policy(vma, addr, ilx); if (!pol) pol = get_task_policy(current); - if (pol->mode == MPOL_INTERLEAVE) { + if (pol->mode == MPOL_INTERLEAVE || + pol->mode == MPOL_WEIGHTED_INTERLEAVE) { *ilx += vma->vm_pgoff >> order; *ilx += (addr - vma->vm_start) >> (PAGE_SHIFT + order); } @@ -1835,6 +1857,28 @@ bool apply_policy_zone(struct mempolicy *policy, enum zone_type zone) return zone >= dynamic_policy_zone; } +static unsigned int weighted_interleave_nodes(struct mempolicy *policy) +{ + unsigned int next; + struct task_struct *me = current; + u8 __rcu *table; + + next = next_node_in(me->il_prev, policy->nodes); + if (next == MAX_NUMNODES) + return next; + + rcu_read_lock(); + table = rcu_dereference(iw_table); + if (!policy->wil.cur_weight) + policy->wil.cur_weight = table ? table[next] : 1; + rcu_read_unlock(); + + policy->wil.cur_weight--; + if (!policy->wil.cur_weight) + me->il_prev = next; + return next; +} + /* Do dynamic interleaving for a process */ static unsigned int interleave_nodes(struct mempolicy *policy) { @@ -1869,6 +1913,9 @@ unsigned int mempolicy_slab_node(void) case MPOL_INTERLEAVE: return interleave_nodes(policy); + case MPOL_WEIGHTED_INTERLEAVE: + return weighted_interleave_nodes(policy); + case MPOL_BIND: case MPOL_PREFERRED_MANY: { @@ -1907,6 +1954,39 @@ static unsigned int read_once_policy_nodemask(struct mempolicy *pol, return nodes_weight(*mask); } +static unsigned int weighted_interleave_nid(struct mempolicy *pol, pgoff_t ilx) +{ + nodemask_t nodemask; + unsigned int target, nr_nodes; + u8 __rcu *table; + unsigned int weight_total = 0; + u8 weight; + int nid; + + nr_nodes = read_once_policy_nodemask(pol, &nodemask); + if (!nr_nodes) + return numa_node_id(); + + rcu_read_lock(); + table = rcu_dereference(iw_table); + /* calculate the total weight */ + for_each_node_mask(nid, nodemask) + weight_total += table ? table[nid] : 1; + + /* Calculate the node offset based on totals */ + target = ilx % weight_total; + nid = first_node(nodemask); + while (target) { + weight = table ? table[nid] : 1; + if (target < weight) + break; + target -= weight; + nid = next_node_in(nid, nodemask); + } + rcu_read_unlock(); + return nid; +} + /* * Do static interleaving for interleave index @ilx. Returns the ilx'th * node in pol->nodes (starting from ilx=0), wrapping around if ilx @@ -1967,6 +2047,11 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *pol, *nid = (ilx == NO_INTERLEAVE_INDEX) ? interleave_nodes(pol) : interleave_nid(pol, ilx); break; + case MPOL_WEIGHTED_INTERLEAVE: + *nid = (ilx == NO_INTERLEAVE_INDEX) ? + weighted_interleave_nodes(pol) : + weighted_interleave_nid(pol, ilx); + break; } return nodemask; @@ -2028,6 +2113,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask) case MPOL_PREFERRED_MANY: case MPOL_BIND: case MPOL_INTERLEAVE: + case MPOL_WEIGHTED_INTERLEAVE: *mask = mempolicy->nodes; break; @@ -2127,7 +2213,8 @@ struct page *alloc_pages_mpol(gfp_t gfp, unsigned int order, * If the policy is interleave or does not allow the current * node in its nodemask, we allocate the standard way. */ - if (pol->mode != MPOL_INTERLEAVE && + if ((pol->mode != MPOL_INTERLEAVE && + pol->mode != MPOL_WEIGHTED_INTERLEAVE) && (!nodemask || node_isset(nid, *nodemask))) { /* * First, try to allocate THP only on local node, but @@ -2263,6 +2350,135 @@ static unsigned long alloc_pages_bulk_array_interleave(gfp_t gfp, return total_allocated; } +static unsigned long alloc_pages_bulk_array_weighted_interleave(gfp_t gfp, + struct mempolicy *pol, unsigned long nr_pages, + struct page **page_array) +{ + struct task_struct *me = current; + unsigned long total_allocated = 0; + unsigned long nr_allocated; + unsigned long rounds; + unsigned long node_pages, delta; + u8 weight, resume_weight; + u8 __rcu *table; + u8 *weights; + unsigned int weight_total = 0; + unsigned long rem_pages = nr_pages; + nodemask_t nodes; + int nnodes, node, weight_nodes, resume_node; + int prev_node = NUMA_NO_NODE; + bool delta_depleted = false; + int i; + + if (!nr_pages) + return 0; + + nnodes = read_once_policy_nodemask(pol, &nodes); + if (!nnodes) + return 0; + + /* Continue allocating from most recent node and adjust the nr_pages */ + if (pol->wil.cur_weight) { + node = next_node_in(me->il_prev, nodes); + node_pages = pol->wil.cur_weight; + if (node_pages > rem_pages) + node_pages = rem_pages; + nr_allocated = __alloc_pages_bulk(gfp, node, NULL, node_pages, + NULL, page_array); + page_array += nr_allocated; + total_allocated += nr_allocated; + /* if that's all the pages, no need to interleave */ + if (rem_pages <= pol->wil.cur_weight) { + pol->wil.cur_weight -= rem_pages; + return total_allocated; + } + /* Otherwise we adjust nr_pages down, and continue from there */ + rem_pages -= pol->wil.cur_weight; + pol->wil.cur_weight = 0; + prev_node = node; + } + + /* fetch the weights for this operation and calculate total weight */ + weights = kmalloc(nnodes, GFP_KERNEL); + if (!weights) + return total_allocated; + + rcu_read_lock(); + table = rcu_dereference(iw_table); + weight_nodes = 0; + while (weight_nodes < nnodes) { + node = next_node_in(prev_node, nodes); + weight = table ? table[node] : 1; + weights[weight_nodes++] = weight; + weight_total += weight; + } + rcu_read_unlock(); + + /* + * Now we can continue allocating from 0 instead of an offset + * We calculate the number of rounds and any partial rounds so + * that we minimize the number of calls to __alloc_pages_bulk + * This requires us to track which node we should resume from. + * + * if (rounds > 0) and (delta == 0), resume_node will always be + * the current me->il_prev + * + * if (delta > 0) and delta is depleted exactly on a node-weight + * boundary, resume node will be the node last allocated from when + * delta reached 0. + * + * if (delta > 0) and delta is not depleted on a node-weight boundary, + * resume node will be the node prior to the node last allocated from. + * + * (rounds == 0) and (delta == 0) is not possible (earlier exit) + */ + rounds = rem_pages / weight_total; + delta = rem_pages % weight_total; + /* If no delta, we'll resume from current prev_node and first weight */ + for (i = 0; i < nnodes; i++) { + node = next_node_in(prev_node, nodes); + weight = weights[i]; + node_pages = weight * rounds; + /* If a delta exists, add this node's portion of the delta */ + if (delta >= weight) { + node_pages += weight; + delta -= weight; + resume_node = node; + resume_weight = i < (nnodes - 1) ? weights[i+1] : + weights[0]; + /* stop tracking iff (delta == weight) */ + delta_depleted = !delta; + } else if (delta) { /* <= weight */ + /* if delta depleted, resume from this node */ + node_pages += delta; + delta = 0; + resume_node = prev_node; + resume_weight = weight - (node_pages % weight); + delta_depleted = true; /* stop tracking */ + } else if (!delta_depleted) { + /* if there was no delta, track last allocated node */ + resume_node = node; + resume_weight = i < (nnodes - 1) ? weights[i+1] : + weights[0]; + } + /* node_pages can be 0 if an allocation fails and rounds == 0 */ + if (!node_pages) + break; + nr_allocated = __alloc_pages_bulk(gfp, node, NULL, node_pages, + NULL, page_array); + page_array += nr_allocated; + total_allocated += nr_allocated; + if (total_allocated == nr_pages) + break; + prev_node = node; + } + /* resume allocating from the calculated node and weight */ + me->il_prev = resume_node; + pol->wil.cur_weight = resume_weight; + kfree(weights); + return total_allocated; +} + static unsigned long alloc_pages_bulk_array_preferred_many(gfp_t gfp, int nid, struct mempolicy *pol, unsigned long nr_pages, struct page **page_array) @@ -2303,6 +2519,10 @@ unsigned long alloc_pages_bulk_array_mempolicy(gfp_t gfp, return alloc_pages_bulk_array_interleave(gfp, pol, nr_pages, page_array); + if (pol->mode == MPOL_WEIGHTED_INTERLEAVE) + return alloc_pages_bulk_array_weighted_interleave( + gfp, pol, nr_pages, page_array); + if (pol->mode == MPOL_PREFERRED_MANY) return alloc_pages_bulk_array_preferred_many(gfp, numa_node_id(), pol, nr_pages, page_array); @@ -2378,6 +2598,7 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b) case MPOL_INTERLEAVE: case MPOL_PREFERRED: case MPOL_PREFERRED_MANY: + case MPOL_WEIGHTED_INTERLEAVE: return !!nodes_equal(a->nodes, b->nodes); case MPOL_LOCAL: return true; @@ -2514,6 +2735,10 @@ int mpol_misplaced(struct folio *folio, struct vm_area_struct *vma, polnid = interleave_nid(pol, ilx); break; + case MPOL_WEIGHTED_INTERLEAVE: + polnid = weighted_interleave_nid(pol, ilx); + break; + case MPOL_PREFERRED: if (node_isset(curnid, pol->nodes)) goto out; @@ -2888,6 +3113,7 @@ static const char * const policy_modes[] = [MPOL_PREFERRED] = "prefer", [MPOL_BIND] = "bind", [MPOL_INTERLEAVE] = "interleave", + [MPOL_WEIGHTED_INTERLEAVE] = "weighted interleave", [MPOL_LOCAL] = "local", [MPOL_PREFERRED_MANY] = "prefer (many)", }; @@ -2947,6 +3173,7 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) } break; case MPOL_INTERLEAVE: + case MPOL_WEIGHTED_INTERLEAVE: /* * Default to online nodes with memory if no nodelist */ @@ -3057,6 +3284,7 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) case MPOL_PREFERRED_MANY: case MPOL_BIND: case MPOL_INTERLEAVE: + case MPOL_WEIGHTED_INTERLEAVE: nodes = pol->nodes; break; default:
When a system has multiple NUMA nodes and it becomes bandwidth hungry, using the current MPOL_INTERLEAVE could be an wise option. However, if those NUMA nodes consist of different types of memory such as socket-attached DRAM and CXL/PCIe attached DRAM, the round-robin based interleave policy does not optimally distribute data to make use of their different bandwidth characteristics. Instead, interleave is more effective when the allocation policy follows each NUMA nodes' bandwidth weight rather than a simple 1:1 distribution. This patch introduces a new memory policy, MPOL_WEIGHTED_INTERLEAVE, enabling weighted interleave between NUMA nodes. Weighted interleave allows for proportional distribution of memory across multiple numa nodes, preferably apportioned to match the bandwidth of each node. For example, if a system has 1 CPU node (0), and 2 memory nodes (0,1), with bandwidth of (100GB/s, 50GB/s) respectively, the appropriate weight distribution is (2:1). Weights for each node can be assigned via the new sysfs extension: /sys/kernel/mm/mempolicy/weighted_interleave/ For now, the default value of all nodes will be `1`, which matches the behavior of standard 1:1 round-robin interleave. An extension will be added in the future to allow default values to be registered at kernel and device bringup time. The policy allocates a number of pages equal to the set weights. For example, if the weights are (2,1), then 2 pages will be allocated on node0 for every 1 page allocated on node1. The new flag MPOL_WEIGHTED_INTERLEAVE can be used in set_mempolicy(2) and mbind(2). There are 3 integration points: weighted_interleave_nodes: Counts the number of allocations as they occur, and applies the weight for the current node. When the weight reaches 0, switch to the next node. weighted_interleave_nid: Gets the total weight of the nodemask as well as each individual node weight, then calculates the node based on the given index. bulk_array_weighted_interleave: Gets the total weight of the nodemask as well as each individual node weight, then calculates the number of "interleave rounds" as well as any delta ("partial round"). Calculates the number of pages for each node and allocates them. If a node was scheduled for interleave via interleave_nodes, the current weight (pol->cur_weight) will be allocated first, before the remaining bulk calculation is done. One piece of complexity is the interaction between a recent refactor which split the logic to acquire the "ilx" (interleave index) of an allocation and the actually application of the interleave. The calculation of the `interleave index` is done by `get_vma_policy()`, while the actual selection of the node will be later appliex by the relevant weighted_interleave function. Suggested-by: Hasan Al Maruf <Hasan.Maruf@amd.com> Signed-off-by: Gregory Price <gregory.price@memverge.com> Co-developed-by: Rakie Kim <rakie.kim@sk.com> Signed-off-by: Rakie Kim <rakie.kim@sk.com> Co-developed-by: Honggyu Kim <honggyu.kim@sk.com> Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> Co-developed-by: Hyeongtak Ji <hyeongtak.ji@sk.com> Signed-off-by: Hyeongtak Ji <hyeongtak.ji@sk.com> Co-developed-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> Signed-off-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> Co-developed-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> --- .../admin-guide/mm/numa_memory_policy.rst | 9 + include/linux/mempolicy.h | 5 + include/uapi/linux/mempolicy.h | 1 + mm/mempolicy.c | 234 +++++++++++++++++- 4 files changed, 246 insertions(+), 3 deletions(-)