From: William Cohen <wcohen@redhat.com>
To: Ankita Garg <ankita@in.ibm.com>,
systemtap@sources.redhat.com, prerna@linux.vnet.ibm.com
Subject: Re: Stap scripts to track task cpu changes
Date: Thu, 09 Jul 2009 14:26:00 -0000 [thread overview]
Message-ID: <4A55FE12.6050803@redhat.com> (raw)
In-Reply-To: <20090619114151.GA13999@in.ibm.com>
[-- Attachment #1: Type: text/plain, Size: 815 bytes --]
Ankita Garg wrote:
> Hello folks,
>
> Quite sometime back, I was faced with a situation where I needed to
> track instances when a particular task was being migrated away from a
> cpu. I used the following trivial script. The tid needs to be passed as
> parameter. Sharing it, hoping it might be useful for some folks.
I would like to add these example to the systemtap examples. I have looked
through them and made some tweaks. For both of them I formatted them not to use
tabs so they can used in documentation.
For chng_cpu.stp use the appropriate probe point, scheduler.cpu_on. Why the
check for "tid() != 0"?
For migrate.stp The check "$1 != 0" seemed to be unneeded. Was there a reason
for using $p->pid and kernel_string($p->comm) rather tid() and execname()? The
test is using "tid() == $1"
-Will
[-- Attachment #2: chng_cpu2.stp --]
[-- Type: text/plain, Size: 1059 bytes --]
/* Filename: chng_cpu.stp
* Author: Ankita Garg <ankita@in.ibm.com>
* Description: Captures information on the number of times an executable
* switches cpu
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Copyright (C) IBM Corp. 2009. All Rights Reserved.
*
*/
global threads
probe scheduler.cpu_on
{
if ((threads[tid()] != cpu()) && (tid() != 0) && (execname() == @1)) {
printf("thread %d (%s) context switched on %d \n",
tid(), execname(), cpu());
printf("state: %d\n", task_state(task_current()))
print_stack(backtrace())
}
threads[tid()] = cpu();
}
[-- Attachment #3: migrate2.stp --]
[-- Type: text/plain, Size: 907 bytes --]
/* Filename: migrate.stp
* Author: Ankita Garg <ankita@in.ibm.com>
* Description: Captures information on the migration of a thread
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Copyright (C) IBM Corp. 2009. All Rights Reserved.
*
*/
probe kernel.function("__migrate_task")
{
if(tid() == $1) {
printf ("thread %d (%s) is migrating from %d to %d \n",
$p->pid, kernel_string($p->comm), $src_cpu, $dest_cpu);
}
}
next prev parent reply other threads:[~2009-07-09 14:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-19 11:42 Ankita Garg
2009-07-09 14:26 ` William Cohen [this message]
[not found] <200907130937.32782.varunc@linux.vnet.ibm.com>
2009-07-13 4:18 ` Ankita Garg
2009-07-13 20:07 ` William Cohen
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=4A55FE12.6050803@redhat.com \
--to=wcohen@redhat.com \
--cc=ankita@in.ibm.com \
--cc=prerna@linux.vnet.ibm.com \
--cc=systemtap@sources.redhat.com \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).