| Message ID | 20240819-numa_policy-v1-1-f096cff543ee@gentwo.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Reenable NUMA policy support in the slab allocator | expand |
On Mon, Aug 19, 2024 at 11:54 AM Christoph Lameter via B4 Relay <devnull+cl.gentwo.org@kernel.org> wrote: > > From: Christoph Lameter <cl@gentwo.org> > > Revert commit 8014c46ad991 ("slub: use alloc_pages_node() in alloc_slab_page()"). > > The patch disabled the numa policy support in the slab allocator. It > did not consider that alloc_pages() uses memory policies but > alloc_pages_node() does not. > > As a result of this patch slab memory allocations are no longer spread via > interleave policy across all available NUMA nodes on bootup. Instead > all slab memory is allocated close to the boot processor. This leads to > an imbalance of memory accesses on NUMA systems. > > Also applications using MPOL_INTERLEAVE as a memory policy will no longer > spread slab allocations over all nodes in the interleave set but allocate > memory locally. This may also result in unbalanced allocations > on a single numa node. > > SLUB does not apply memory policies to individual object allocations. > However, it relies on the page allocators support of memory policies > through alloc_pages() to do the NUMA memory allocations on a per > folio or page level. SLUB also applies memory policies when retrieving > partial allocated slab pages from the partial list. > > Fixes: 8014c46ad991 ("slub: use alloc_pages_node() in alloc_slab_page()") > Cc: stable@kernel.org > Signed-off-by: Christoph Lameter <cl@gentwo.org> Reviewed-by: Yang Shi <shy828301@gmail.com> > --- > mm/slub.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index c9d8a2497fd6..4dea3c7df5ad 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2318,7 +2318,11 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node, > struct slab *slab; > unsigned int order = oo_order(oo); > > - folio = (struct folio *)alloc_pages_node(node, flags, order); > + if (node == NUMA_NO_NODE) > + folio = (struct folio *)alloc_pages(flags, order); > + else > + folio = (struct folio *)__alloc_pages_node(node, flags, order); > + > if (!folio) > return NULL; > > > --- > base-commit: b0da640826ba3b6506b4996a6b23a429235e6923 > change-id: 20240806-numa_policy-5188f44ba0d8 > > Best regards, > -- > Christoph Lameter <cl@gentwo.org> > >
On 8/19/24 20:54, Christoph Lameter via B4 Relay wrote: > From: Christoph Lameter <cl@gentwo.org> > > Revert commit 8014c46ad991 ("slub: use alloc_pages_node() in alloc_slab_page()"). > > The patch disabled the numa policy support in the slab allocator. It > did not consider that alloc_pages() uses memory policies but > alloc_pages_node() does not. > > As a result of this patch slab memory allocations are no longer spread via > interleave policy across all available NUMA nodes on bootup. Instead > all slab memory is allocated close to the boot processor. This leads to > an imbalance of memory accesses on NUMA systems. > > Also applications using MPOL_INTERLEAVE as a memory policy will no longer > spread slab allocations over all nodes in the interleave set but allocate > memory locally. This may also result in unbalanced allocations > on a single numa node. > > SLUB does not apply memory policies to individual object allocations. > However, it relies on the page allocators support of memory policies > through alloc_pages() to do the NUMA memory allocations on a per > folio or page level. SLUB also applies memory policies when retrieving > partial allocated slab pages from the partial list. > > Fixes: 8014c46ad991 ("slub: use alloc_pages_node() in alloc_slab_page()") > Cc: stable@kernel.org I'm removing this as (unlike the stable tree maintainers) I try to follow the stable tree rules, and this wouldn't apply by them. Also it's a revert of 6.8 commit, so the LTS kernel 6.6 doesn't care anyway. > Signed-off-by: Christoph Lameter <cl@gentwo.org> Thanks, added to slab/for-next > --- > mm/slub.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index c9d8a2497fd6..4dea3c7df5ad 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2318,7 +2318,11 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node, > struct slab *slab; > unsigned int order = oo_order(oo); > > - folio = (struct folio *)alloc_pages_node(node, flags, order); > + if (node == NUMA_NO_NODE) > + folio = (struct folio *)alloc_pages(flags, order); > + else > + folio = (struct folio *)__alloc_pages_node(node, flags, order); > + > if (!folio) > return NULL; > > > --- > base-commit: b0da640826ba3b6506b4996a6b23a429235e6923 > change-id: 20240806-numa_policy-5188f44ba0d8 > > Best regards,
diff --git a/mm/slub.c b/mm/slub.c index c9d8a2497fd6..4dea3c7df5ad 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2318,7 +2318,11 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node, struct slab *slab; unsigned int order = oo_order(oo); - folio = (struct folio *)alloc_pages_node(node, flags, order); + if (node == NUMA_NO_NODE) + folio = (struct folio *)alloc_pages(flags, order); + else + folio = (struct folio *)__alloc_pages_node(node, flags, order); + if (!folio) return NULL;