From: Ankita Garg <ankita@in.ibm.com>
To: systemtap@sources.redhat.com
Cc: prerna@linux.vnet.ibm.com
Subject: Stap scripts to track task cpu changes
Date: Fri, 19 Jun 2009 11:42:00 -0000 [thread overview]
Message-ID: <20090619114151.GA13999@in.ibm.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 2768 bytes --]
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.
/* Filename: migrate.stp
* Author: Ankita Garg <ankita@in.ibm.com>
* Description: Captures information on the migration of threads
*
* 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 IBM Corp. 2009. All Rights Reserved.
*
*/
probe kernel.function("__migrate_task")
{
if(($1 != 0 ) && (tid() == $1)) {
printf ("thread %d (%s) is migrating from %d to %d \n", $p->pid,
kernel_string($p->comm), $src_cpu, $dest_cpu);
}
}
Below is a script that tracks all the cpus that a particular task ran
on. Pl note it does not track the context switches.
/* Filename: chng_cpu.stp
* Author: Ankita Garg <ankita@in.ibm.com>
* Description: Captures information on the number of times java thread
* 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 IBM Corp. 2009. All Rights Reserved.
*
*/
global threads
probe kernel.function("finish_task_switch")
{
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();
}
With the new tracepoints infrastructure, the above stats could maybe be
captured in a much easier way, however, it worked well with stap as well
:-) Do let me know if you have any suggestions.
--
Regards,
Ankita Garg (ankita@in.ibm.com)
Linux Technology Center
IBM India Systems & Technology Labs,
Bangalore, India
[-- Attachment #2: migrate.stp --]
[-- Type: text/plain, Size: 910 bytes --]
/* Filename: migrate.stp
* Author: Ankita Garg <ankita@in.ibm.com>
* Description: Captures information on the migration of threads
*
* 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 IBM Corp. 2009. All Rights Reserved.
*
*/
probe kernel.function("__migrate_task")
{
if(($1 != 0 ) && (tid() == $1)) {
printf ("thread %d (%s) is migrating from %d to %d \n", $p->pid,
kernel_string($p->comm), $src_cpu, $dest_cpu);
}
}
[-- Attachment #3: chng_cpu.stp --]
[-- Type: text/plain, Size: 1120 bytes --]
/* Filename: chng_cpu.stp
* Author: Ankita Garg <ankita@in.ibm.com>
* Description: Captures information on the number of times java thread
* 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 IBM Corp. 2009. All Rights Reserved.
*
*/
global threads
probe kernel.function("finish_task_switch")
{
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();
}
next reply other threads:[~2009-06-19 11:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-19 11:42 Ankita Garg [this message]
2009-07-09 14:26 ` William Cohen
[not found] <200907130937.32782.varunc@linux.vnet.ibm.com>
2009-07-13 4:18 ` Ankita Garg
2009-07-13 20:07 ` William Cohen
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