linux-kernel - Re: [PATCH 33/37] perf bench futex: Cache align the worker struct

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Message-ID: <94c3f945b1f11c799d4ec4ab5a0efc90@suse.de>
Date:   Mon, 24 Oct 2016 11:50:50 -0700
From:   Davidlohr Bueso <dbueso@...e.de>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 33/37] perf bench futex: Cache align the worker struct

On 2016-10-24 09:20, Arnaldo Carvalho de Melo wrote:
> From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> 
> It popped up in perf testing that the worker consumes some amount of
> CPU. It boils down to the increment of `ops` which causes cache line
> bouncing between the individual threads.
> 
> This patch aligns the struct by 256 bytes to ensure that not a cache
> line is shared among CPUs. 128 byte is the x86 worst case and grep says
> that L1_CACHE_SHIFT is set to 8 on s390.

Hmm so this one should have been replaced with this:

https://marc.info/?l=linux-kernel&m=147690008801082

Thanks,
Davidlohr