lkml.org 
[lkml]   [2009]   [Dec]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/4] ftrace - add function_duration tracer

* Frank Ch. Eigler <fche@redhat.com> wrote:

> Ingo Molnar <mingo@elte.hu> writes:
>
> > [...]
> > Just off the top of my head we want to be able to trace:
> >
> > - max irq service latencies for a given IRQ
> > - max block IO completion latencies for a app
> > - max TLB flush latencies in the system
> > - max sys_open() latencies in a task
> > - max fork()/exit() latencies in a workload
> > - max scheduling latencies on a given CPU
> > - max page fault latencies
> > - max wakeup latencies for a given task
> > - max memory allocation latencies
> >
> > - ... and dozens and dozens of other things where there's a "start"
> > and a "stop" event and where we want to measure the time between
> > them.
> > [...]
>
> FWIW, those who want to collect such measurements today can do so with
> a few lines of systemtap script for each of the above.

Well, i dont think stap can do workload instrumentation. It can do
system-wide (and user local / task local) - but can it do per task
hierarchies?

Also, i dont think stap supports proper separation of per workload
measurements either. I.e. can you write a script that will work properly
even if multiple monitoring tools are running, each trying to measure
latencies?

Also, i personally find built-in kernel functionality more trustable
than dynamically built stap kernel modules that get inserted.

Ingo


\
 
 \ /
  Last update: 2009-12-10 19:01    [W:0.126 / U:0.268 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site