Philippe Gerum wrote:
> Dmitry Adamushko wrote:
> >
> > Hello all,
> > e.g. it took 1 minute and 30 seconds to get 21 lines of statistics on
> > the screen (-p 100) but should have been ~22-23 seconds.
> >
> > And the latency thread really reported the presence of collected data 21
> > times (through rt_sem_v()) .
> >
> > So have I missed something important? any ideas are wellcome.
> >
>
> Dunno yet, but this reminds me of a trap I've been into recently that
> caused a massive slowdown of the latency test (v2.0.x) whilst the
> reported real-time activity seemed to be ok. Weird enough, actually. The
> explanation was that I mistakenly left the full ACPI support and SUSPEND
> active in my kernel config (Asus box with ICH6 chipset). Shutting them
> down solved the issue. I've not investigated further which one of the
> ACPI options or SUSPEND caused that trouble yet.
I am observing a similar issue here; after a suspend/resume cycle,
running the latency test gives low latencies and every second is at
least two seconds long.
If I load the cpufreq module, I notice that even if when suspending,
/proc/cpuinfo indicates 1.5 GHz, after resuming, it indicates 600 MHz.
So, maybe, when doing a suspend/resume cycle without the CPUFreq modules
loaded, Linux assumes that the CPU frequency remains the same whereas
ACPI/BIOS changes it ?
--
Gilles Chanteperdrix.
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