linux-kernel - Re: [RFC PATCH v6] sched: Fix performance regression introduced by mm

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Date:   Fri, 14 Apr 2023 17:43:17 +0800
From:   Aaron Lu <aaron.lu@...el.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
CC:     Peter Zijlstra <peterz@...radead.org>,
        <linux-kernel@...r.kernel.org>, Olivier Dion <odion@...icios.com>,
        <michael.christie@...cle.com>
Subject: Re: [RFC PATCH v6] sched: Fix performance regression introduced by
 mm_cid

On Thu, Apr 13, 2023 at 06:33:56PM -0400, Mathieu Desnoyers wrote:
> Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL
> sysbench regression reported by Aaron Lu.

No lock contention from cid.

For postgres_sysbench:
mm_cid_get() is in the range of 0.2% - 1.2% during a 5 minutes run.
Other cid functions are pretty minor.

For hackbench:
mm_cid_get() is in the range of 2.x% - 7.x%. Other cid functions are
pretty minor.