* tracefs .. idea
@ 2012-10-16 10:44 Lars Segerlund
2012-10-16 11:04 ` John Kacur
0 siblings, 1 reply; 2+ messages in thread
From: Lars Segerlund @ 2012-10-16 10:44 UTC (permalink / raw)
To: linux-rt-users
I was thinking of tracking locks and above all interrupt disable
through debugfs.
Something along the lines of a buffer with the top offenders in it,
and thus getting a list of the longest latency introducing sections.
Or would it be 'better' to instrument with something like kprobes and
have a utility for this functionality ?
Any further idea of stuff to trace ? or has this already been done
and I am unaware of it ?
I basicly want a list of the sections in the kernel that disables
preemption for the longest time.
/ regards, Lars Segerlund.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: tracefs .. idea
2012-10-16 10:44 tracefs .. idea Lars Segerlund
@ 2012-10-16 11:04 ` John Kacur
0 siblings, 0 replies; 2+ messages in thread
From: John Kacur @ 2012-10-16 11:04 UTC (permalink / raw)
To: Lars Segerlund; +Cc: linux-rt-users
On Tue, 16 Oct 2012, Lars Segerlund wrote:
> I was thinking of tracking locks and above all interrupt disable
> through debugfs.
>
> Something along the lines of a buffer with the top offenders in it,
> and thus getting a list of the longest latency introducing sections.
> Or would it be 'better' to instrument with something like kprobes and
> have a utility for this functionality ?
>
> Any further idea of stuff to trace ? or has this already been done
> and I am unaware of it ?
>
> I basicly want a list of the sections in the kernel that disables
> preemption for the longest time.
Hi Lars - Have a look at ftrace, I think it does what you are looking for.
In the kernel source read, Documentation/trace/ftrace.txt
Look at "preemptoff" to see how to record the amount of time preemption is
disabled.
John
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