From: Matthew Wilcox <willy@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
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
Date: Mon, 7 Jan 2019 08:14:42 -0800 [thread overview]
Message-ID: <20190107161442.GZ6310@bombadil.infradead.org> (raw)
In-Reply-To: <c2ef7231-fe1f-9463-0b06-e88f990aa865@redhat.com>
On Mon, Jan 07, 2019 at 11:07:47AM -0500, Waiman Long wrote:
> > Why are you caching the _output_ of calling sprintf(), rather than caching the
> > values of each interrupt?
> >
> It is just faster to dump the whole string buffer than redoing the
> number formatting each time when the values don't change. I can cache
> the individual sums instead if it is the preferred by most.
But it also consumes more memory. Can you gather some measurements to
find out what the performance difference is if you cache the values
instead of the strings?
next prev parent reply other threads:[~2019-01-07 16:14 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-07 15:12 [PATCH 0/2] /proc/stat: Reduce irqs counting performance overhead Waiman Long
2019-01-07 15:12 ` [PATCH 1/2] /proc/stat: Extract irqs counting code into show_stat_irqs() Waiman Long
2019-01-07 21:42 ` Kees Cook
2019-01-07 15:12 ` [PATCH 2/2] /proc/stat: Add sysctl parameter to control irq counts latency Waiman Long
2019-01-07 15:58 ` Matthew Wilcox
2019-01-07 16:07 ` Waiman Long
2019-01-07 16:14 ` Matthew Wilcox [this message]
2019-01-07 16:19 ` Waiman Long
2019-01-07 16:33 ` Alexey Dobriyan
2019-01-07 16:59 ` Waiman Long
[not found] ` <20190118084456.GA10690@shao2-debian>
2019-01-21 20:02 ` [LKP] [/proc/stat] 3047027b34: reaim.jobs_per_min -4.8% regression Kees Cook
2019-01-21 21:25 ` Alexey Dobriyan
2019-01-07 22:32 ` [PATCH 0/2] /proc/stat: Reduce irqs counting performance overhead Dave Chinner
2019-01-07 22:41 ` Daniel Colascione
2019-01-07 23:49 ` Alexey Dobriyan
2019-01-07 22:41 ` Waiman Long
2019-01-08 2:04 ` Dave Chinner
2019-01-08 16:11 ` Michal Hocko
2019-01-08 17:05 ` Waiman Long
2019-01-08 17:32 ` Waiman Long
2019-01-08 16:58 ` Waiman Long
2019-01-08 22:27 ` Dave Chinner
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