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Date:   Mon, 7 Jan 2019 19:33:01 +0300
From:   Alexey Dobriyan <adobriyan@gmail.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Waiman Long <longman@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Jonathan Corbet <corbet@lwn.net>, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Davidlohr Bueso <dave@stgolabs.net>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Daniel Colascione <dancol@google.com>,
        Dave Chinner <david@fromorbit.com>,
        Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH 2/2] /proc/stat: Add sysctl parameter to control irq
 counts latency
Message-ID: <20190107163301.GA14354@avx2>
References: <1546873978-27797-1-git-send-email-longman@redhat.com>
 <1546873978-27797-3-git-send-email-longman@redhat.com>
 <20190107155840.GY6310@bombadil.infradead.org>
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On Mon, Jan 07, 2019 at 07:58:40AM -0800, Matthew Wilcox wrote:
> On Mon, Jan 07, 2019 at 10:12:58AM -0500, Waiman Long wrote:

> > A new "fs/proc-stat-irqs-latency-ms" sysctl parameter is now added to
> 
> No.  No, no, no, no, no.  No.
> 
> Stop adding new sysctls for this kind of thing.  It's just a way to shift
> blame from us (who allegedly know what we're doing) to the sysadmin
> (who probably has better things to be doing than keeping up with the
> intricacies of development of every single piece of software running on
> their system).
> 
> Let's figure out what this _should_ be.

Yeah, let's start interrogating about which values specifically this
super sekret applications wants.

I assume CPU stats, so system call which returns CPU statistics in binary form.

> Why are you caching the _output_ of calling sprintf(), rather than caching the
> values of each interrupt?

For output caching string is better, but I'm not defending the patch.