Re: How can i track all process context switches in the kernel ?

[Johannes Weiner <hannes@xxxxxxxxxxxx>]

Hi,

"Manish Katiyar" <mkatiyar@xxxxxxxxx> writes:

> On Sat, May 17, 2008 at 11:55 AM, Indraneel Mukherjee
> <mukherjee.indraneel@xxxxxxxxx> wrote:
>> Hi All,
>> I'm looking for a way to track the sequence in which processes were
>> scheduled by the scheduler. Just the sequence in which processes were
>> scheduled like 23,34 45,665, 34 ....
>>  I think it can be done by inserting a printk at some appropriate
>> place in the scheduler but i'm not sure were. Can i get some pointers
>> in that direction? Is there any other easy way?
>
> How about adding something like in the function schedule() in  kernel/sched.c
>
>    printk(KERN_CRIT "Scheduling process [%u] \n",current->tgid);

On a mostly idling machine I get between 40 and 100 context switches per
second.  I doubt you want to have this printk().

Better have the scheduler push every new PID on a ring of limited size
and make the items readable in that order via /proc.

	Hannes

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