From: Shailabh Nagar <nagar@watson.ibm.com>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [Patch 1/4] Delay accounting: Initialization
Date: Tue, 15 Nov 2005 10:08:57 -0500 [thread overview]
Message-ID: <4379FA09.3040807@watson.ibm.com> (raw)
In-Reply-To: <20051114202017.6f8c0327.akpm@osdl.org>
Andrew Morton wrote:
> Shailabh Nagar <nagar@watson.ibm.com> wrote:
>
>>+ *ts = sched_clock();
>
>
> I'm not sure that it's kosher to use sched_clock() for fine-grained
> timestamping like this. Ingo had issues with it last time this happened?
>
> <too lazy to read all the code> Do you normalise these numbers in some
> manner before presenting them to userspace? If so, by what means?
The cpu delay data collected by schedstats (which is jiffies based)
is normalized to nanosecs. The timestamps based on sched_clock() are exported
as is. As Marcelo pointed out, thats not good enough since sched_clock() itself
could return jiffie-based resolution. So some normalization will be needed for
that data as well.
next prev parent reply other threads:[~2005-11-15 15:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-15 4:35 [Patch 1/4] Delay accounting: Initialization Shailabh Nagar
2005-11-15 4:20 ` Andrew Morton
2005-11-15 6:49 ` Marcelo Tosatti
2005-11-15 15:19 ` Shailabh Nagar
2005-11-15 12:20 ` Marcelo Tosatti
2005-11-15 12:34 ` Marcelo Tosatti
2005-11-15 15:08 ` Shailabh Nagar [this message]
2005-11-16 1:06 ` Peter Chubb
2005-11-16 1:48 ` Shailabh Nagar
2005-11-16 1:50 ` Andi Kleen
2005-11-16 1:52 ` Peter Chubb
2005-11-15 4:25 ` Parag Warudkar
2005-11-15 22:29 ` Shailabh Nagar
2005-11-15 22:53 ` Parag Warudkar
2005-11-16 0:45 ` Shailabh Nagar
2005-11-16 2:41 ` Parag Warudkar
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=4379FA09.3040807@watson.ibm.com \
--to=nagar@watson.ibm.com \
--cc=akpm@osdl.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
/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