Messages in this thread | | | Date | Wed, 15 Mar 2006 10:40:34 -0400 | From | "Mauricio Lin" <> | Subject | Re: Jiffy is not able to measure the fraction of time a process runs a processor |
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Hi all,
I have managed to measure the cpu time in nanoseconds. On i386 I have used the monotonic_clock() to measure the cpu time accurately.
The cpu time measurements were based on t->sched_info.cpu_time, but instead of accumulate the all cpu time, I needed just the diff=jiffies -t->sched_info.last_arrival in the sched_info_depart().
The problem was most of time the diff was zero. So to solve this problem I used the monotonic_clock() function that provides more accurate way to measure cpu time.
Any comments?
On 14 Mar 2006 15:54:17 -0500, Frank Ch. Eigler <fche@redhat.com> wrote: > "Mauricio Lin" <mauriciolin@gmail.com> writes: > > > I am trying to measure the fraction of time a process runs on a > > processor, but the jiffies is not able to provide an accurate value. > > See sched_clock().
I have checked it. It helped me to reach the monotonic_clock() function after hacking the code.
> > > The example below [...] > > PID : NAME : LAST ARRIVAL : CPU TIME : CALLER > > 4544 : kmix : 6170433 : 0 : work_resched+0x6c > > 4078 : lpd : 6170433 : 0 : __down_interruptible+0x5 > > 4544 : kmix : 6170433 : 0 : schedule_timeout+0xb8 > > What tool/patchset are you using to generate this trace?
I am using the relayfs to report the information I need among the processors. I just put some klog in some key points in the code.
BR,
Mauricio Lin. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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