The quilt patch titled
Subject: memcg: increase MEMCG_CHARGE_BATCH to 64
has been removed from the -mm tree. Its filename was
memcg-increase-memcg_charge_batch-to-64.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: memcg: increase MEMCG_CHARGE_BATCH to 64
Date: Thu, 25 Aug 2022 00:05:06 +0000
For several years, MEMCG_CHARGE_BATCH was kept at 32 but with bigger
machines and the network intensive workloads requiring througput in Gbps,
32 is too small and makes the memcg charging path a bottleneck. For now,
increase it to 64 for easy acceptance to 6.0. We will need to revisit
this in future for ever increasing demand of higher performance.
Please note that the memcg charge path drain the per-cpu memcg charge
stock, so there should not be any oom behavior change. Though it does
have impact on rstat flushing and high limit reclaim backoff.
To evaluate the impact of this optimization, on a 72 CPUs machine, we
ran the following workload in a three level of cgroup hierarchy.
$ netserver -6
# 36 instances of netperf with following params
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
Results (average throughput of netperf):
Without (6.0-rc1) 10482.7 Mbps
With patch 17064.7 Mbps (62.7% improvement)
With the patch, the throughput improved by 62.7%.
Link: https://lkml.kernel.org/r/20220825000506.239406-4-shakeelb@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Acked-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Reviewed-by: Feng Tang <feng.tang@xxxxxxxxx>
Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Acked-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: "Michal Koutný" <mkoutny@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/include/linux/memcontrol.h~memcg-increase-memcg_charge_batch-to-64
+++ a/include/linux/memcontrol.h
@@ -354,10 +354,11 @@ struct mem_cgroup {
};
/*
- * size of first charge trial. "32" comes from vmscan.c's magic value.
- * TODO: maybe necessary to use big numbers in big irons.
+ * size of first charge trial.
+ * TODO: maybe necessary to use big numbers in big irons or dynamic based of the
+ * workload.
*/
-#define MEMCG_CHARGE_BATCH 32U
+#define MEMCG_CHARGE_BATCH 64U
extern struct mem_cgroup *root_mem_cgroup;
_
Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are
mm-deduplicate-cacheline-padding-code.patch
memcg-extract-memcg_vmstats-from-struct-mem_cgroup.patch
memcg-rearrange-code.patch
memcg-reduce-size-of-memcg-vmstats-structures.patch
