| Message ID | 20210127233345.339910-9-shy828301@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Make shrinker's nr_deferred memcg aware | expand |
On Fri, Jan 29, 2021 at 6:59 AM Kirill Tkhai <ktkhai@virtuozzo.com> wrote: > > On 29.01.2021 17:55, Kirill Tkhai wrote: > > On 28.01.2021 02:33, Yang Shi wrote: > >> Use per memcg's nr_deferred for memcg aware shrinkers. The shrinker's nr_deferred > >> will be used in the following cases: > >> 1. Non memcg aware shrinkers > >> 2. !CONFIG_MEMCG > >> 3. memcg is disabled by boot parameter > >> > >> Signed-off-by: Yang Shi <shy828301@gmail.com> > >> --- > >> mm/vmscan.c | 87 ++++++++++++++++++++++++++++++++++++++++++++--------- > >> 1 file changed, 73 insertions(+), 14 deletions(-) > >> > >> diff --git a/mm/vmscan.c b/mm/vmscan.c > >> index 20be0db291fe..e1f8960f5cf6 100644 > >> --- a/mm/vmscan.c > >> +++ b/mm/vmscan.c > >> @@ -205,7 +205,8 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg, > >> > >> for_each_node(nid) { > >> old = rcu_dereference_protected( > >> - mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, true); > >> + mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, > >> + lockdep_is_held(&shrinker_rwsem)); > > > > Won't it better to pack this repeating pattern into helper function, e.g.: > > > > static struct shrinker_info memcg_shrinker_info(struct mem_cgroup *memcg, int nid) > > { > > return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, > > lockdep_is_held(&shrinker_rwsem)); > > } > > > > ? > > > > Even shrink_slab_memcg() may want to use it. > > Hm, I see you already introduced a helper in [10/11], but it is used in only place. > Then, we should use it for all places (introduce the helper earlier). Yes, good point. Will fix in v6. > > >> /* Not yet online memcg */ > >> if (!old) > >> return 0; > >> @@ -239,7 +240,8 @@ void free_shrinker_info(struct mem_cgroup *memcg) > >> > >> for_each_node(nid) { > >> pn = mem_cgroup_nodeinfo(memcg, nid); > >> - info = rcu_dereference_protected(pn->shrinker_info, true); > >> + info = rcu_dereference_protected(pn->shrinker_info, > >> + lockdep_is_held(&shrinker_rwsem)); > >> if (info) > >> kvfree(info); > >> rcu_assign_pointer(pn->shrinker_info, NULL); > >> @@ -360,6 +362,27 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) > >> up_write(&shrinker_rwsem); > >> } > >> > >> +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker, > >> + struct mem_cgroup *memcg) > >> +{ > >> + struct shrinker_info *info; > >> + > >> + info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, > >> + lockdep_is_held(&shrinker_rwsem)); > >> + return atomic_long_xchg(&info->nr_deferred[shrinker->id], 0); > >> +} > >> + > >> +static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, > >> + struct mem_cgroup *memcg) > >> +{ > >> + struct shrinker_info *info; > >> + > >> + info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, > >> + lockdep_is_held(&shrinker_rwsem)); > >> + > >> + return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); > >> +} > >> + > >> static bool cgroup_reclaim(struct scan_control *sc) > >> { > >> return sc->target_mem_cgroup; > >> @@ -398,6 +421,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) > >> { > >> } > >> > >> +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker, > >> + struct mem_cgroup *memcg) > >> +{ > >> + return 0; > >> +} > >> + > >> +static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, > >> + struct mem_cgroup *memcg) > >> +{ > >> + return 0; > >> +} > >> + > >> static bool cgroup_reclaim(struct scan_control *sc) > >> { > >> return false; > >> @@ -409,6 +444,39 @@ static bool writeback_throttling_sane(struct scan_control *sc) > >> } > >> #endif > >> > >> +static long count_nr_deferred(struct shrinker *shrinker, > >> + struct shrink_control *sc) > >> +{ > >> + int nid = sc->nid; > >> + > >> + if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > >> + nid = 0; > >> + > >> + if (sc->memcg && > >> + (shrinker->flags & SHRINKER_MEMCG_AWARE)) > >> + return count_nr_deferred_memcg(nid, shrinker, > >> + sc->memcg); > >> + > >> + return atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > >> +} > >> + > >> + > >> +static long set_nr_deferred(long nr, struct shrinker *shrinker, > >> + struct shrink_control *sc) > >> +{ > >> + int nid = sc->nid; > >> + > >> + if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > >> + nid = 0; > >> + > >> + if (sc->memcg && > >> + (shrinker->flags & SHRINKER_MEMCG_AWARE)) > >> + return set_nr_deferred_memcg(nr, nid, shrinker, > >> + sc->memcg); > >> + > >> + return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]); > >> +} > >> + > >> /* > >> * This misses isolated pages which are not accounted for to save counters. > >> * As the data only determines if reclaim or compaction continues, it is > >> @@ -545,14 +613,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > >> long freeable; > >> long nr; > >> long new_nr; > >> - int nid = shrinkctl->nid; > >> long batch_size = shrinker->batch ? shrinker->batch > >> : SHRINK_BATCH; > >> long scanned = 0, next_deferred; > >> > >> - if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > >> - nid = 0; > >> - > >> freeable = shrinker->count_objects(shrinker, shrinkctl); > >> if (freeable == 0 || freeable == SHRINK_EMPTY) > >> return freeable; > >> @@ -562,7 +626,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > >> * and zero it so that other concurrent shrinker invocations > >> * don't also do this scanning work. > >> */ > >> - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > >> + nr = count_nr_deferred(shrinker, shrinkctl); > >> > >> total_scan = nr; > >> if (shrinker->seeks) { > >> @@ -653,14 +717,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > >> next_deferred = 0; > >> /* > >> * move the unused scan count back into the shrinker in a > >> - * manner that handles concurrent updates. If we exhausted the > >> - * scan, there is no need to do an update. > >> + * manner that handles concurrent updates. > >> */ > >> - if (next_deferred > 0) > >> - new_nr = atomic_long_add_return(next_deferred, > >> - &shrinker->nr_deferred[nid]); > >> - else > >> - new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); > >> + new_nr = set_nr_deferred(next_deferred, shrinker, shrinkctl); > >> > >> trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan); > >> return freed; > >> > > > >
On Fri, Jan 29, 2021 at 7:13 AM Vlastimil Babka <vbabka@suse.cz> wrote: > > On 1/28/21 12:33 AM, Yang Shi wrote: > > Use per memcg's nr_deferred for memcg aware shrinkers. The shrinker's nr_deferred > > will be used in the following cases: > > 1. Non memcg aware shrinkers > > 2. !CONFIG_MEMCG > > 3. memcg is disabled by boot parameter > > > > Signed-off-by: Yang Shi <shy828301@gmail.com> > > --- > > mm/vmscan.c | 87 ++++++++++++++++++++++++++++++++++++++++++++--------- > > 1 file changed, 73 insertions(+), 14 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 20be0db291fe..e1f8960f5cf6 100644 > > ... > > > @@ -653,14 +717,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > > next_deferred = 0; > > /* > > * move the unused scan count back into the shrinker in a > > - * manner that handles concurrent updates. If we exhausted the > > - * scan, there is no need to do an update. > > + * manner that handles concurrent updates. > > */ > > - if (next_deferred > 0) > > - new_nr = atomic_long_add_return(next_deferred, > > - &shrinker->nr_deferred[nid]); > > - else > > - new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); > > Why not keep this write avoidance if next_deferred == 0 in the new helper? Because IMHO the write avoidance may not make too much difference since nr_deferred was updated for the most cases per my tracing result. So I thought this would make the code more clean. > > > + new_nr = set_nr_deferred(next_deferred, shrinker, shrinkctl); > > > > trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan); > > return freed; > > >
diff --git a/mm/vmscan.c b/mm/vmscan.c index 20be0db291fe..e1f8960f5cf6 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -205,7 +205,8 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg, for_each_node(nid) { old = rcu_dereference_protected( - mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, true); + mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, + lockdep_is_held(&shrinker_rwsem)); /* Not yet online memcg */ if (!old) return 0; @@ -239,7 +240,8 @@ void free_shrinker_info(struct mem_cgroup *memcg) for_each_node(nid) { pn = mem_cgroup_nodeinfo(memcg, nid); - info = rcu_dereference_protected(pn->shrinker_info, true); + info = rcu_dereference_protected(pn->shrinker_info, + lockdep_is_held(&shrinker_rwsem)); if (info) kvfree(info); rcu_assign_pointer(pn->shrinker_info, NULL); @@ -360,6 +362,27 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) up_write(&shrinker_rwsem); } +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker, + struct mem_cgroup *memcg) +{ + struct shrinker_info *info; + + info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, + lockdep_is_held(&shrinker_rwsem)); + return atomic_long_xchg(&info->nr_deferred[shrinker->id], 0); +} + +static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, + struct mem_cgroup *memcg) +{ + struct shrinker_info *info; + + info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, + lockdep_is_held(&shrinker_rwsem)); + + return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); +} + static bool cgroup_reclaim(struct scan_control *sc) { return sc->target_mem_cgroup; @@ -398,6 +421,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) { } +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker, + struct mem_cgroup *memcg) +{ + return 0; +} + +static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, + struct mem_cgroup *memcg) +{ + return 0; +} + static bool cgroup_reclaim(struct scan_control *sc) { return false; @@ -409,6 +444,39 @@ static bool writeback_throttling_sane(struct scan_control *sc) } #endif +static long count_nr_deferred(struct shrinker *shrinker, + struct shrink_control *sc) +{ + int nid = sc->nid; + + if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) + nid = 0; + + if (sc->memcg && + (shrinker->flags & SHRINKER_MEMCG_AWARE)) + return count_nr_deferred_memcg(nid, shrinker, + sc->memcg); + + return atomic_long_xchg(&shrinker->nr_deferred[nid], 0); +} + + +static long set_nr_deferred(long nr, struct shrinker *shrinker, + struct shrink_control *sc) +{ + int nid = sc->nid; + + if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) + nid = 0; + + if (sc->memcg && + (shrinker->flags & SHRINKER_MEMCG_AWARE)) + return set_nr_deferred_memcg(nr, nid, shrinker, + sc->memcg); + + return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]); +} + /* * This misses isolated pages which are not accounted for to save counters. * As the data only determines if reclaim or compaction continues, it is @@ -545,14 +613,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, long freeable; long nr; long new_nr; - int nid = shrinkctl->nid; long batch_size = shrinker->batch ? shrinker->batch : SHRINK_BATCH; long scanned = 0, next_deferred; - if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) - nid = 0; - freeable = shrinker->count_objects(shrinker, shrinkctl); if (freeable == 0 || freeable == SHRINK_EMPTY) return freeable; @@ -562,7 +626,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, * and zero it so that other concurrent shrinker invocations * don't also do this scanning work. */ - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); + nr = count_nr_deferred(shrinker, shrinkctl); total_scan = nr; if (shrinker->seeks) { @@ -653,14 +717,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, next_deferred = 0; /* * move the unused scan count back into the shrinker in a - * manner that handles concurrent updates. If we exhausted the - * scan, there is no need to do an update. + * manner that handles concurrent updates. */ - if (next_deferred > 0) - new_nr = atomic_long_add_return(next_deferred, - &shrinker->nr_deferred[nid]); - else - new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); + new_nr = set_nr_deferred(next_deferred, shrinker, shrinkctl); trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan); return freed;
Use per memcg's nr_deferred for memcg aware shrinkers. The shrinker's nr_deferred will be used in the following cases: 1. Non memcg aware shrinkers 2. !CONFIG_MEMCG 3. memcg is disabled by boot parameter Signed-off-by: Yang Shi <shy828301@gmail.com> --- mm/vmscan.c | 87 ++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 73 insertions(+), 14 deletions(-)