The patch titled
Subject: cgroup: rename cgroup_rstat_flush_"irqsafe" to "atomic"
has been added to the -mm mm-unstable branch. Its filename is
cgroup-rename-cgroup_rstat_flush_irqsafe-to-atomic.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/cgroup-rename-cgroup_rstat_flush_irqsafe-to-atomic.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Subject: cgroup: rename cgroup_rstat_flush_"irqsafe" to "atomic"
Date: Thu, 30 Mar 2023 19:17:54 +0000
Patch series "memcg: avoid flushing stats atomically where possible", v3.
rstat flushing is an expensive operation that scales with the number of
cpus and the number of cgroups in the system. The purpose of this series
is to minimize the contexts where we flush stats atomically.
Patches 1 and 2 are cleanups requested during reviews of prior versions of
this series.
Patch 3 makes sure we never try to flush from within an irq context.
Patches 4 to 7 introduce separate variants of mem_cgroup_flush_stats() for
atomic and non-atomic flushing, and make sure we only flush the stats
atomically when necessary.
Patch 8 is a slightly tangential optimization that limits the work done by
rstat flushing in some scenarios.
This patch (of 8):
cgroup_rstat_flush_irqsafe() can be a confusing name. It may read as
"irqs are disabled throughout", which is what the current implementation
does (currently under discussion [1]), but is not the intention. The
intention is that this function is safe to call from atomic contexts.
Name it as such.
Link: https://lkml.kernel.org/r/20230330191801.1967435-1-yosryahmed@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20230330191801.1967435-2-yosryahmed@xxxxxxxxxx
Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Suggested-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Michal Koutný <mkoutny@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vasily Averin <vasily.averin@xxxxxxxxx>
Cc: Zefan Li <lizefan.x@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cgroup.h | 2 +-
kernel/cgroup/rstat.c | 4 ++--
mm/memcontrol.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
--- a/include/linux/cgroup.h~cgroup-rename-cgroup_rstat_flush_irqsafe-to-atomic
+++ a/include/linux/cgroup.h
@@ -692,7 +692,7 @@ static inline void cgroup_path_from_kern
*/
void cgroup_rstat_updated(struct cgroup *cgrp, int cpu);
void cgroup_rstat_flush(struct cgroup *cgrp);
-void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp);
+void cgroup_rstat_flush_atomic(struct cgroup *cgrp);
void cgroup_rstat_flush_hold(struct cgroup *cgrp);
void cgroup_rstat_flush_release(void);
--- a/kernel/cgroup/rstat.c~cgroup-rename-cgroup_rstat_flush_irqsafe-to-atomic
+++ a/kernel/cgroup/rstat.c
@@ -241,12 +241,12 @@ __bpf_kfunc void cgroup_rstat_flush(stru
}
/**
- * cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush()
+ * cgroup_rstat_flush_atomic- atomic version of cgroup_rstat_flush()
* @cgrp: target cgroup
*
* This function can be called from any context.
*/
-void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
+void cgroup_rstat_flush_atomic(struct cgroup *cgrp)
{
unsigned long flags;
--- a/mm/memcontrol.c~cgroup-rename-cgroup_rstat_flush_irqsafe-to-atomic
+++ a/mm/memcontrol.c
@@ -643,7 +643,7 @@ static void __mem_cgroup_flush_stats(voi
return;
flush_next_time = jiffies_64 + 2*FLUSH_TIME;
- cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup);
+ cgroup_rstat_flush_atomic(root_mem_cgroup->css.cgroup);
atomic_set(&stats_flush_threshold, 0);
spin_unlock_irqrestore(&stats_flush_lock, flag);
}
_
Patches currently in -mm which might be from yosryahmed@xxxxxxxxxx are
cgroup-rename-cgroup_rstat_flush_irqsafe-to-atomic.patch
memcg-rename-mem_cgroup_flush_stats_delayed-to-ratelimited.patch
memcg-do-not-flush-stats-in-irq-context.patch
memcg-replace-stats_flush_lock-with-an-atomic.patch
memcg-sleep-during-flushing-stats-in-safe-contexts.patch
workingset-memcg-sleep-when-flushing-stats-in-workingset_refault.patch
vmscan-memcg-sleep-when-flushing-stats-during-reclaim.patch
memcg-do-not-modify-rstat-tree-for-zero-updates.patch
