From: Chris Down <chris@chrisdown.name>
To: Feng Tang <feng.tang@intel.com>
Cc: Shakeel Butt <shakeelb@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
andi.kleen@intel.com, "Chen, Tim C" <tim.c.chen@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Huang Ying <ying.huang@intel.com>, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH 2/2] mm: memcg: add a new MEMCG_UPDATE_BATCH
Date: Wed, 6 Jan 2021 03:43:36 +0000 [thread overview]
Message-ID: <X/Ux6CT6EsP+QQ8S@chrisdown.name> (raw)
In-Reply-To: <20210106021213.GD101866@shbuild999.sh.intel.com>
Feng Tang writes:
>One further thought is, there are quite some "BATCH" number in
>kernel for perf-cpu/global data updating, maybe we can add a
>global flag 'sysctl_need_accurate_stats' for
> if (sysctl_need_accurate_stats)
> batch = SMALLER_BATCH
> else
> batch = BIGGER_BATCH
Moving decisions like this to the system administrator is not really a solution
to the problem -- inclusion should at least be contingent on either having
"correct-ish" stats exported to userspace. Displaying broken stats to the user
-- even with a configuration knob -- is less than ideal and is likely to
confuse and confound issues in future.
I would also like to see numbers from more real-world workloads.
MEMCG_CHARGE_BATCH is certainly fairly arbitrary as-is, but if it is going to
be changed, the reason for that change and its implications (positive and
negative) for real-world workloads must be well understood, and I'm not sure
we're there yet.
next prev parent reply other threads:[~2021-01-06 3:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 14:35 [PATCH 1/2] mm: page_counter: relayout structure to reduce false sharing Feng Tang
2020-12-29 14:35 ` [PATCH 2/2] mm: memcg: add a new MEMCG_UPDATE_BATCH Feng Tang
2020-12-29 17:13 ` Roman Gushchin
2021-01-04 2:53 ` Feng Tang
2021-01-04 7:46 ` [mm] 4d8191276e: vm-scalability.throughput 43.4% improvement kernel test robot
2021-01-04 13:15 ` [PATCH 2/2] mm: memcg: add a new MEMCG_UPDATE_BATCH Michal Hocko
2021-01-05 1:57 ` Feng Tang
2021-01-06 0:47 ` Shakeel Butt
2021-01-06 2:12 ` Feng Tang
2021-01-06 3:43 ` Chris Down [this message]
2021-01-06 3:45 ` Chris Down
2021-01-06 4:45 ` Feng Tang
2020-12-29 16:56 ` [PATCH 1/2] mm: page_counter: relayout structure to reduce false sharing Roman Gushchin
2020-12-30 14:19 ` Feng Tang
2021-01-04 13:03 ` Michal Hocko
2021-01-04 13:34 ` Feng Tang
2021-01-04 14:11 ` Michal Hocko
2021-01-04 14:44 ` Feng Tang
2021-01-04 15:34 ` Michal Hocko
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