From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: apolyakov@beget.ru, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, aryabinin@virtuozzo.com,
akpm@linux-foundation.org
Subject: Re: [PATCH 3/3] mm: Count list_lru_one::nr_items lockless
Date: Wed, 23 Aug 2017 11:27:12 +0300 [thread overview]
Message-ID: <20170823082712.tw6qtyllctn25puq@esperanza> (raw)
In-Reply-To: <b1600bca-32cc-e285-8589-778999584d5a@virtuozzo.com>
On Wed, Aug 23, 2017 at 11:00:56AM +0300, Kirill Tkhai wrote:
> On 22.08.2017 22:47, Vladimir Davydov wrote:
> > On Tue, Aug 22, 2017 at 03:29:35PM +0300, Kirill Tkhai wrote:
> >> During the reclaiming slab of a memcg, shrink_slab iterates
> >> over all registered shrinkers in the system, and tries to count
> >> and consume objects related to the cgroup. In case of memory
> >> pressure, this behaves bad: I observe high system time and
> >> time spent in list_lru_count_one() for many processes on RHEL7
> >> kernel (collected via $perf record --call-graph fp -j k -a):
> >>
> >> 0,50% nixstatsagent [kernel.vmlinux] [k] _raw_spin_lock [k] _raw_spin_lock
> >> 0,26% nixstatsagent [kernel.vmlinux] [k] shrink_slab [k] shrink_slab
> >> 0,23% nixstatsagent [kernel.vmlinux] [k] super_cache_count [k] super_cache_count
> >> 0,15% nixstatsagent [kernel.vmlinux] [k] __list_lru_count_one.isra.2 [k] _raw_spin_lock
> >> 0,15% nixstatsagent [kernel.vmlinux] [k] list_lru_count_one [k] __list_lru_count_one.isra.2
> >>
> >> 0,94% mysqld [kernel.vmlinux] [k] _raw_spin_lock [k] _raw_spin_lock
> >> 0,57% mysqld [kernel.vmlinux] [k] shrink_slab [k] shrink_slab
> >> 0,51% mysqld [kernel.vmlinux] [k] super_cache_count [k] super_cache_count
> >> 0,32% mysqld [kernel.vmlinux] [k] __list_lru_count_one.isra.2 [k] _raw_spin_lock
> >> 0,32% mysqld [kernel.vmlinux] [k] list_lru_count_one [k] __list_lru_count_one.isra.2
> >>
> >> 0,73% sshd [kernel.vmlinux] [k] _raw_spin_lock [k] _raw_spin_lock
> >> 0,35% sshd [kernel.vmlinux] [k] shrink_slab [k] shrink_slab
> >> 0,32% sshd [kernel.vmlinux] [k] super_cache_count [k] super_cache_count
> >> 0,21% sshd [kernel.vmlinux] [k] __list_lru_count_one.isra.2 [k] _raw_spin_lock
> >> 0,21% sshd [kernel.vmlinux] [k] list_lru_count_one [k] __list_lru_count_one.isra.2
> >
> > It would be nice to see how this is improved by this patch.
> > Can you try to record the traces on the vanilla kernel with
> > and without this patch?
>
> Sadly, the talk is about a production node, and it's impossible to use vanila kernel there.
I see :-( Then maybe you could try to come up with a contrived test?
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next prev parent reply other threads:[~2017-08-23 8:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-22 12:29 [PATCH 0/3] Make count list_lru_one::nr_items lockless Kirill Tkhai
2017-08-22 12:29 ` [PATCH 1/3] mm: Add rcu field to struct list_lru_memcg Kirill Tkhai
2017-08-22 12:29 ` [PATCH 2/3] mm: Make list_lru_node::memcg_lrus RCU protected Kirill Tkhai
2017-08-22 19:34 ` Vladimir Davydov
2017-08-22 12:29 ` [PATCH 3/3] mm: Count list_lru_one::nr_items lockless Kirill Tkhai
2017-08-22 19:47 ` Vladimir Davydov
2017-08-23 8:00 ` Kirill Tkhai
2017-08-23 8:27 ` Vladimir Davydov [this message]
2017-08-23 12:26 ` Kirill Tkhai
2017-08-26 17:57 ` Vladimir Davydov
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