Messages in this thread | | | Date | Mon, 22 Nov 2010 13:23:06 +0100 | From | Florian Mickler <> | Subject | Re: [PATCH 3/5] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies |
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On Mon, 22 Nov 2010 11:43:59 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, 2010-11-22 at 06:51 +0100, Florian Mickler wrote: > > On Sat, 20 Nov 2010 11:48:24 +0100 > > Peter Zijlstra <peterz@infradead.org> wrote: > > > > > On Fri, 2010-11-19 at 18:08 -0800, John Stultz wrote: > > > > From: Mike Chan <mike@android.com> > > > > > > > > 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. > > Dude, its from the _android_ tree... its cpufreq crud.. it must be some > crack induced power management scheme. > >
:)
what I wanted to get at, was that they probably need these stats aggregated somewhere neat and tidy and can not compute them on the fly recording massive amounts of data...
I wonder why they didn't put this in the idle-driver. I don't know.
Regards, Flo
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