From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Tomasz Buchert <tomasz.buchert@inria.fr>
Cc: linux-kernel@vger.kernel.org,
Daniel Walker <dwalker@codeaurora.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 0/4] Wall time clocks + change in access rules
Date: Fri, 30 Jul 2010 13:23:43 +0200 [thread overview]
Message-ID: <20100730132343.4c15bfdc@dhcp-lab-109.englab.brq.redhat.com> (raw)
In-Reply-To: <1280483867-6387-1-git-send-email-tomasz.buchert@inria.fr>
Hi Tomasz
On Fri, 30 Jul 2010 11:57:43 +0200
Tomasz Buchert <tomasz.buchert@inria.fr> wrote:
> During our work we encountered a problem of obtaining
> a reliable and fine-grained measurements of CPU time/wall time
> of a process/thread. The existing methods (taskstats, procfs,
> POSIX CPU clocks) have either unfriendly interface (taskstats)
Well, "unfriendly" is not technical word ... Taskstat was designed
as extensible method to provide statistics to user space, including
some special needs like yours. What your patches basically do, is get
the value of wall_time(p) = uptime - p->start_time . I do not see
any reason why this calculation can not be done in userspace, getting
uptime and p->start_time from kernel by existing methods (or adding
new one for p->start_time if precise method does not really exist).
Is enough to read p->start_time only once at the beginning, this value
does not change.
Anyway, I think we need better rationale, before we can consider your wall
clock patches inclusion into the kernel.
BTW: If you will repost please cc Thomas Gleixner as he is kernel/*timers*
maintainer.
Cheers
Stanislaw
next prev parent reply other threads:[~2010-07-30 11:24 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-30 9:57 Tomasz Buchert
2010-07-30 9:57 ` [PATCH 1/4] posix-timers: Refactoring of CPUCLOCK* macros Tomasz Buchert
2010-07-30 9:57 ` [PATCH 2/4] posix-cpu-timers: Introduction of wall clocks Tomasz Buchert
2010-07-30 9:57 ` [PATCH 3/4] posix-cpu-timers: Wider access to the thread clocks Tomasz Buchert
2010-07-30 9:57 ` [PATCH 4/4] posix-cpu-timers: posix-cpu-timers.c renamed to posix-task-timers.c Tomasz Buchert
2010-07-30 11:30 ` [PATCH 2/4] posix-cpu-timers: Introduction of wall clocks Stanislaw Gruszka
2010-07-30 11:23 ` Stanislaw Gruszka [this message]
2010-07-30 11:51 ` [PATCH 0/4] Wall time clocks + change in access rules Stanislaw Gruszka
2010-07-30 14:58 ` Rationale for wall clocks Tomasz Buchert
-- strict thread matches above, loose matches on Subject: below --
2010-07-19 21:02 [PATCH 1/4] posix-timers: Refactoring of CPUCLOCK* macros Daniel Walker
2010-07-21 18:03 ` [PATCH 0/4] Wall time clocks + change in access rules Tomasz Buchert
2010-07-19 11:34 Tomasz Buchert
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=20100730132343.4c15bfdc@dhcp-lab-109.englab.brq.redhat.com \
--to=sgruszka@redhat.com \
--cc=dwalker@codeaurora.org \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=tomasz.buchert@inria.fr \
/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
all inboxes | Powered by JetHome®