linux-kernel - Re: [PATCH v2 0/4] /proc/stat: Reduce irqs counting performance overhead

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Date:   Wed, 9 Jan 2019 10:24:17 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Davidlohr Bueso <dave@...olabs.net>,
        Miklos Szeredi <miklos@...redi.hu>,
        Daniel Colascione <dancol@...gle.com>,
        Dave Chinner <david@...morbit.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v2 0/4] /proc/stat: Reduce irqs counting performance
 overhead

On Wed, Jan 09, 2019 at 01:03:33PM -0500, Waiman Long wrote:
> The paragraph above may be a bit misleading. This v2 patch actually
> touches very little on percpu accounting aspect of the IRQ counts. See
> patches 2 and 3 for the relevant changes which is just a few line of new
> codes. Please review the individual patches before Nak'ing.
> 
> I could theoretically generalize them into a new set of percpu counting
> helpers, but the idea behind it is quite different from the use cases of
> percpu counter. So it may not be a good idea of adding it to there.

Did you even try just using the general purpose infrastructure that's
in place?  If that shows a performance problem _then_ it's time to make
this special snowflake just a little more special.  Not before.