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

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Message-ID: <20190109174403.GN6310@bombadil.infradead.org>
Date:   Wed, 9 Jan 2019 09:44:03 -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 12:23:44PM -0500, Waiman Long wrote:
> This v2 patch optimizes the way the IRQ counts are retrieved and computed
> and getting rid of the sysctl parameter altogether to achieve a performance
> gain that is close to the v1 patch. This is based on the idea that while
> many IRQs can be supported by a system, only a handful of them are actually
> being used in most cases. We can save a lot of time by focusing on those
> active IRQs only and ignore the rests.

So your reaction to being told "Make this the same as every other thing
we have to sum across all CPUs" is to make it _even more different_ and
special-cased?  I'm done.  NAK.