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

From: Arnaldo Carvalho de Melo
Date: Mon Oct 24 2016 - 14:53:36 EST


Em Mon, Oct 24, 2016 at 11:50:50AM -0700, Davidlohr Bueso escreveu:
> On 2016-10-24 09:20, Arnaldo Carvalho de Melo wrote:
> > From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> >
> > 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

Humm, sorry, can you please send a patch fixing this?

- Arnaldo