[lkml]   [2010]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 3/5] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies
On Sat, 20 Nov 2010 11:48:24 +0100
Peter Zijlstra <> wrote:

> On Fri, 2010-11-19 at 18:08 -0800, John Stultz wrote:
> > From: Mike Chan <>
> >
> > Introduce new platform callback hooks for cpuacct for tracking CPU frequencies
> >
> > Not all platforms / architectures have a set CPU_FREQ_TABLE defined
> > for CPU transition speeds. In order to track time spent in at various
> > CPU frequencies, we enable platform callbacks from cpuacct for this accounting.
> >
> > Architectures that support overclock boosting, or don't have pre-defined
> > frequency tables can implement their own bucketing system that makes sense
> > given their cpufreq scaling abilities.
> >
> > New file:
> > cpuacct.cpufreq reports the CPU time (in nanoseconds) spent at each CPU
> > frequency.
> I utterly detest all such accounting crap.. it adds ABI constraints it
> add runtime overhead. etc..
> Can't you get the same information by using the various perf bits? If
> you trace the cpufreq changes you can compute the time spend in each
> power state, if you additionally trace the sched_switch you can compute
> it for each task.
This is probably used for "on-site" debugging of production systems.

I.e. when someone sends them a problem report using an
bugreport-tool, they gather all useful information they can get on the
system because they only have one-way communication with their bug

Do the perf bits work for such a usecase? If I guess correctly, the
perf bits need a userspace part that computes what would be in the
cpuacct.cpufreq file?


 \ /
  Last update: 2010-11-22 06:55    [W:0.063 / U:1.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site