| Message ID | 20220312071623.19050-1-richard.weiyang@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/3] mm/memcg: mz already removed from rb_tree in mem_cgroup_largest_soft_limit_node() | expand |
On Sat 12-03-22 07:16:21, Wei Yang wrote: > When mz is not NULL, mem_cgroup_largest_soft_limit_node() has removed > it from rb_tree. > > Not necessary to call __mem_cgroup_remove_exceeded() again. Yes, the call seems to be unnecessary with the current code. mz can either come from mem_cgroup_largest_soft_limit_node or __mem_cgroup_largest_soft_limit_node both rely on the latter so the mz is always off the tree indeed. > Signed-off-by: Wei Yang <richard.weiyang@gmail.com> After the changelog is completed you can add Acked-by: Michal Hocko <mhocko@suse.com> In general, though, I am not a super fan of changes like these. The code works as expected, the call for __mem_cgroup_remove_exceeded will not really add much of an overhead and at least we can see that mz is always removed before it is re-added back. In a hot path I would care much more of course but this is effectivelly a dead code as the soft limit itself is mostly a relict of past. Please keep this in mind when you want to make further changes to this area. The review is not free of cost and I am not sure spending time on this area is worthwhile unless there is a real usecase in mind. Thanks! > --- > mm/memcontrol.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index f898320b678a..d70bf5cf04eb 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3458,7 +3458,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, > nr_reclaimed += reclaimed; > *total_scanned += nr_scanned; > spin_lock_irq(&mctz->lock); > - __mem_cgroup_remove_exceeded(mz, mctz); > > /* > * If we failed to reclaim anything from this memory cgroup > -- > 2.33.1
On Mon, Mar 14, 2022 at 10:51:51AM +0100, Michal Hocko wrote: >On Sat 12-03-22 07:16:21, Wei Yang wrote: >> When mz is not NULL, mem_cgroup_largest_soft_limit_node() has removed >> it from rb_tree. >> >> Not necessary to call __mem_cgroup_remove_exceeded() again. > >Yes, the call seems to be unnecessary with the current code. mz can >either come from mem_cgroup_largest_soft_limit_node or >__mem_cgroup_largest_soft_limit_node both rely on the latter so the mz >is always off the tree indeed. > >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com> > >After the changelog is completed you can add >Acked-by: Michal Hocko <mhocko@suse.com> Will adjust it. > >In general, though, I am not a super fan of changes like these. The code >works as expected, the call for __mem_cgroup_remove_exceeded will not >really add much of an overhead and at least we can see that mz is always >removed before it is re-added back. In a hot path I would care much more >of course but this is effectivelly a dead code as the soft limit itself >is mostly a relict of past. > >Please keep this in mind when you want to make further changes to this >area. The review is not free of cost and I am not sure spending time on >this area is worthwhile unless there is a real usecase in mind. > Yes, after more understanding of the code, I found soft reclaim seems to be not that often. Thanks for your time and will choose some more important area for change. >Thanks! > >> --- >> mm/memcontrol.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index f898320b678a..d70bf5cf04eb 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -3458,7 +3458,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, >> nr_reclaimed += reclaimed; >> *total_scanned += nr_scanned; >> spin_lock_irq(&mctz->lock); >> - __mem_cgroup_remove_exceeded(mz, mctz); >> >> /* >> * If we failed to reclaim anything from this memory cgroup >> -- >> 2.33.1 > >-- >Michal Hocko >SUSE Labs
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f898320b678a..d70bf5cf04eb 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3458,7 +3458,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order, nr_reclaimed += reclaimed; *total_scanned += nr_scanned; spin_lock_irq(&mctz->lock); - __mem_cgroup_remove_exceeded(mz, mctz); /* * If we failed to reclaim anything from this memory cgroup
When mz is not NULL, mem_cgroup_largest_soft_limit_node() has removed it from rb_tree. Not necessary to call __mem_cgroup_remove_exceeded() again. Signed-off-by: Wei Yang <richard.weiyang@gmail.com> --- mm/memcontrol.c | 1 - 1 file changed, 1 deletion(-)