linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua>
To: Andrew Morton <akpm@zip.com.au>, Rik van Riel <riel@conectiva.com.br>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC][PATCH] iowait statistics
Date: Wed, 15 May 2002 15:02:57 -0200	[thread overview]
Message-ID: <200205151200.g4FC0MY13196@Port.imtp.ilyichevsk.odessa.ua> (raw)
In-Reply-To: <Pine.LNX.4.44L.0205132214480.32261-100000@imladris.surriel.com> <3CE073FA.57DAC578@zip.com.au>

On 14 May 2002 00:18, Andrew Morton wrote:
> Rik van Riel wrote:
> > 4) on SMP systems the iowait time can be overestimated, no big
> >    deal IMHO but cheap suggestions for improvement are welcome
>
> I suspect that a number of these statistical accounting mechanisms
> are going to break.  The new irq-affinity code works awfully well.
>
> The kernel profiler in 2.5 doesn't work very well at present.
> When investigating this, I ran a busy-wait process.  It attached
> itself to CPU #3 and that CPU received precisely zero interrupts
> across a five minute period.  So the profiler cunningly avoids profiling
> busy CPUs, which is rather counter-productive.  Fortunate that oprofile
> uses NMI.

What, even local APIC interrupts did not happen on CPU#3
in these five mins?
--
vda

  parent reply	other threads:[~2002-05-15 12:09 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-05-14  1:19 [RFC][PATCH] iowait statistics Rik van Riel
2002-05-14  2:18 ` Andrew Morton
2002-05-14 12:30   ` Rik van Riel
2002-05-15 17:02   ` Denis Vlasenko [this message]
2002-05-16  7:41     ` Andrew Morton
2002-05-16 14:04       ` Denis Vlasenko
2002-05-14 15:39 ` William Lee Irwin III
2002-05-14 16:36   ` Rik van Riel
2002-05-14 16:54     ` William Lee Irwin III
2002-05-15 17:17       ` Denis Vlasenko
2002-05-15 14:03         ` Rik van Riel
2002-05-15 20:17           ` Denis Vlasenko
2002-05-15 16:13             ` Rik van Riel
2002-05-15 16:21               ` William Lee Irwin III
2002-05-15 17:00               ` William Lee Irwin III
2002-05-15 18:16                 ` Bill Davidsen
2002-05-15 18:30                 ` William Lee Irwin III
2002-05-15 18:33                   ` Rik van Riel
2002-05-15 18:46                     ` William Lee Irwin III
2002-05-15 19:00                       ` Rik van Riel
2002-05-16 11:42                         ` Denis Vlasenko
2002-05-16 11:14               ` Denis Vlasenko
2002-05-15 15:15         ` Bill Davidsen
2002-05-16 10:58           ` Denis Vlasenko
2002-05-14 18:19     ` Martin J. Bligh
2002-05-15  1:31 ` Bill Davidsen
2002-05-15  1:41   ` William Lee Irwin III
2002-05-15 14:39     ` Bill Davidsen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=200205151200.g4FC0MY13196@Port.imtp.ilyichevsk.odessa.ua \
    --to=vda@port.imtp.ilyichevsk.odessa.ua \
    --cc=akpm@zip.com.au \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=riel@conectiva.com.br \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).