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From: Roman Gushchin <guro@fb.com>
To: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>, <linux-kernel@vger.kernel.org>,
	<cgroups@vger.kernel.org>, <linux-mm@kvack.org>,
	Shakeel Butt <shakeelb@google.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	Chris Down <chris@chrisdown.name>,
	Yafang Shao <laoar.shao@gmail.com>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Wei Yang <richard.weiyang@gmail.com>,
	Masayoshi Mizuma <msys.mizuma@gmail.com>
Subject: Re: [PATCH 0/5] mm/memcg: Reduce kmemcache memory accounting overhead
Date: Mon, 12 Apr 2021 12:05:13 -0700	[thread overview]
Message-ID: <YHSZ6X/DvgddiZBi@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <20210409231842.8840-1-longman@redhat.com>

On Fri, Apr 09, 2021 at 07:18:37PM -0400, Waiman Long wrote:
> With the recent introduction of the new slab memory controller, we
> eliminate the need for having separate kmemcaches for each memory
> cgroup and reduce overall kernel memory usage. However, we also add
> additional memory accounting overhead to each call of kmem_cache_alloc()
> and kmem_cache_free().
> 
> For workloads that require a lot of kmemcache allocations and
> de-allocations, they may experience performance regression as illustrated
> in [1].
> 
> With a simple kernel module that performs repeated loop of 100,000,000
> kmem_cache_alloc() and kmem_cache_free() of 64-byte object at module
> init. The execution time to load the kernel module with and without
> memory accounting were:
> 
>   with accounting = 6.798s
>   w/o  accounting = 1.758s
> 
> That is an increase of 5.04s (287%). With this patchset applied, the
> execution time became 4.254s. So the memory accounting overhead is now
> 2.496s which is a 50% reduction.

Btw, there were two recent independent report about benchmark results
regression caused by the introduction of the per-object accounting:
1) Xing reported a hackbench regression:
https://lkml.org/lkml/2021/1/13/1277
2) Masayoshi reported a pgbench regression:
https://www.spinics.net/lists/linux-mm/msg252540.html

I wonder if you can run them (or at least one) and attach the result
to the series? It would be very helpful.

Thank you!

  parent reply	other threads:[~2021-04-12 19:05 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-09 23:18 [PATCH 0/5] mm/memcg: Reduce kmemcache memory accounting overhead Waiman Long
2021-04-09 23:18 ` [PATCH 1/5] mm/memcg: Pass both memcg and lruvec to mod_memcg_lruvec_state() Waiman Long
2021-04-12 18:04   ` Roman Gushchin
2021-04-12 19:24     ` Waiman Long
2021-04-12 19:22   ` Shakeel Butt
2021-04-09 23:18 ` [PATCH 2/5] mm/memcg: Introduce obj_cgroup_uncharge_mod_state() Waiman Long
2021-04-12 15:50   ` Shakeel Butt
2021-04-12 18:10   ` Roman Gushchin
2021-04-09 23:18 ` [PATCH 3/5] mm/memcg: Cache vmstat data in percpu memcg_stock_pcp Waiman Long
2021-04-12 18:22   ` Roman Gushchin
2021-04-12 19:30     ` Waiman Long
2021-04-09 23:18 ` [PATCH 4/5] mm/memcg: Separate out object stock data into its own struct Waiman Long
2021-04-12 18:53   ` Roman Gushchin
2021-04-09 23:18 ` [PATCH 5/5] mm/memcg: Optimize user context object stock access Waiman Long
2021-04-12 18:55   ` Roman Gushchin
2021-04-12 19:58     ` Waiman Long
2021-04-10  1:51 ` [PATCH 0/5] mm/memcg: Reduce kmemcache memory accounting overhead Roman Gushchin
2021-04-12 14:03   ` Waiman Long
2021-04-12 17:47     ` Roman Gushchin
2021-04-12 19:20       ` Waiman Long
2021-04-12 19:05 ` Roman Gushchin [this message]
2021-04-12 19:51   ` Waiman Long

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