From: Alexey Dobriyan <adobriyan@gmail.com>
To: longman@redhat.com
Cc: linux-kernel@vger.kernel.org, rdunlap@infradead.org
Subject: Re: [PATCH] proc/stat: Separate out individual irq counts into /proc/stat_irqs
Date: Thu, 19 Apr 2018 22:08:46 +0300 [thread overview]
Message-ID: <20180419190846.GE2066@avx2> (raw)
> Therefore, application performance can be impacted if the application
> reads /proc/stat rather frequently.
[nods]
Text interfaces can be designed in a very stupid way.
> For example, reading /proc/stat in a certain 2-socket Skylake server
> took about 4.6ms because it had over 5k irqs.
Is this top(1)? What is this application doing?
If it needs percpu usage stats, then maybe /proc/stat should be
converted away from single_open() so that core seq_file code doesn't
generate everything at once.
> -
> - /* sum again ? it could be updated? */
> - for_each_irq_nr(j)
> - seq_put_decimal_ull(p, " ", kstat_irqs_usr(j));
> -
This is direct userspace breakage.
Proper fix is to start strategic switch away from /proc.
It is a fun toy but its time has come.
next reply other threads:[~2018-04-19 19:08 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-19 19:08 Alexey Dobriyan [this message]
2018-04-19 19:28 ` [PATCH] proc/stat: Separate out individual irq counts into /proc/stat_irqs Waiman Long
2018-04-19 19:55 ` Alexey Dobriyan
[not found] ` <eb7c1569-e445-5cbb-6d10-2694b625232a@redhat.com>
2018-04-19 20:39 ` Alexey Dobriyan
2018-04-19 20:58 ` Waiman Long
2018-04-19 23:23 ` Joel Fernandes (Google)
2018-04-21 20:34 ` Alexey Dobriyan
2018-04-21 20:36 ` Alexey Dobriyan
2018-04-24 5:54 ` David Rientjes
2018-04-24 6:18 ` Alexey Dobriyan
2018-05-02 0:02 ` Andrew Morton
2018-04-19 21:05 ` Waiman Long
-- strict thread matches above, loose matches on Subject: below --
2018-04-19 17:09 Waiman Long
2018-04-19 17:38 ` Randy Dunlap
2018-04-19 18:44 ` Waiman Long
2018-04-19 19:43 ` Andrew Morton
2018-04-19 19:57 ` Waiman Long
2018-04-19 20:02 ` Alexey Dobriyan
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