linux-kernel - Re: [PATCHv2] zsmalloc: allow only one active pool compaction context

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Message-ID: <20230417235855.GR25053@google.com>
Date:   Tue, 18 Apr 2023 08:58:55 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Yosry Ahmed <yosryahmed@...gle.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv2] zsmalloc: allow only one active pool compaction context

On (23/04/17 11:32), Yosry Ahmed wrote:
> > /proc/lock-stat after make -j$((`nproc`+1)) linux kernel for
> > &pool->lock#3:
> >
> >                 Base           Patched
> > ------------------------------------------
> > con-bounces     2035730        1540066
> > contentions     2343871        1774348
> > waittime-min    0.10           0.10
> > waittime-max    4004216.24     2745.22
> > waittime-total  101334168.29   67865414.91
> > waittime-avg    43.23          38.25
> > acq-bounces     2895765        2186745
> > acquisitions    6247686        5136943
> > holdtime-min    0.07           0.07
> > holdtime-max    2605507.97     482439.16
> > holdtime-total  9998599.59     5107151.01
> > holdtime-avg    1.60           0.99
> 
> The numbers seem to be better when using an atomic vs. a mutex, is
> this just noise or significant difference? (I am not familiar with
> lock-stat).

Pretty sure that's just noise. The test is make -j72 on a system
that swaps out, so it's terribly noisy.