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From: Andrew Morton <akpm@linux-foundation.org>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: David Rientjes <rientjes@google.com>,
	"Joel Fernandes (Google)" <joel.opensrc@gmail.com>,
	Waiman Long <longman@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	rdunlap@infradead.org
Subject: Re: [PATCH] proc/stat: Separate out individual irq counts into /proc/stat_irqs
Date: Tue, 1 May 2018 17:02:03 -0700	[thread overview]
Message-ID: <20180501170203.d2b0a99acf0b5288476a11a7@linux-foundation.org> (raw)
In-Reply-To: <20180424061859.GA16181@avx2>

On Tue, 24 Apr 2018 09:18:59 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:

> On Mon, Apr 23, 2018 at 10:54:18PM -0700, David Rientjes wrote:
> > On Sat, 21 Apr 2018, Alexey Dobriyan wrote:
> > 
> > > > On Thu, Apr 19, 2018 at 04:23:02PM -0700, Joel Fernandes (Google) wrote:
> > > > > Can we not just remove per-IRQ stats from /proc/stat (since I gather
> > > > > from this discussion it isn't scalable), and just have applications
> > > > > that need per-IRQ stats use /proc/interrupts ?
> > > > 
> > > > If you can prove noone is using them in /proc/stat...
> > > 
> > > And you can't even stick WARN into /proc/stat to find out.
> > > 
> > 
> > FWIW, removing per irq counts from /proc/stat would break some of our
> > scripts.  We could adapt to that, but everybody else would have to as
> > well, so I'm afraid it's not going to be possible.
> 
> Excellent!
> 
> > It would probably be better to extract out the stats that you're actually
> > interested in to a new file.
> 
> This is the worst scenario. Individual IRQ stats are going to live in 2 places.
> And /proc/stat still would be slow.

No, a new /proc/stat2 which omits the `intr' line would be fast(er). 
Although if we're going to do such a thing we might choose to
reorganize and prune /proc/stat2 even further, and actually put some
thought into it - the current one is a bit of a dog's breakfast.

Dumb question(s):

a) if we moved the `intr' line to the very end of /proc/stat, would
   anything break?  Maybe.

b) if an application were then to read stuff from /proc/stat and
   were to stop reading before it read the `intr' line, would
   its read from /proc/stat still be slow?

c) if the answer to b) is "yes" then can we change that?  Only go
   off and prepare the `intr' line if the application is really truly
   reading it in?

  reply	other threads:[~2018-05-02  0:02 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 19:08 Alexey Dobriyan
2018-04-19 19:28 ` 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 [this message]
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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