Op 3-dec.-2013, om 13:23 heeft Gilles Chanteperdrix het volgende geschreven:
> On 12/03/2013 02:07 PM, Kurijn Buys wrote:
>> Thanks for the quick response, ACPI is enabled, I only disabled
>> "Processor" in there... -1 was a typo indeed, it is at 1... I see
>> SCHED_SMT [=y] in my kernel config... shall I recompile the kernel
>> with this disabled then... no other things to try first/at the same
>> time?
>
> To remove hyperthreading, either:
> - disable it in the BIOS configuration;
> - or disable CONFIG_SMP (not SCHED_SMPT) in the kernel configuration.
>
Ah I see, CONFIG_SMP is also enabled...
I've disabled it in BIOS, but no success (tell me if it is worth trying to
disable it in the kernel config in stead).
>>
>> I realized that the test with sched_rt_runtime_us on -1 I performed
>> was with an earlier set-up. When I set it now to -1, I have better
>> performance, but: 1) still spikes of up to 87us under load with
>> ./latency 2) still some completely shifted occurrences with the other
>> latency test, with a 1000µs period (but now only 2 out of 890814),
>> and the rest of the distribution lies in [861-1139]µs, which is also
>> rather large I suppose.
>
> sched_rt_runtime_us should not make any difference.
>
> Something else you should try is to disable root thread priority coupling.
>
I have tried a config with priority coupling support disabled before, but then
the system was even more vulnerable for such latency peaks (however the mean
latency was a little lower!)
(I still have the kernel, but unfortunately the I-pipe tracer isn't installed
there)
>>
>> The ipipe trace after test (1) was similar to the one I posted, where
>> this line seems to be the problem I suppose: :| #end 0x80000001
>> -179! 149.235 ipipe_check_context+0x87 (add_preempt_count+0x15)
>>
...I hoped the I-pipe trace would help..?
>> Merci! ]{urijn
>
> You are welcome. Please avoid top-posting.
>
> Regards.
>
> --
> Gilles.
-- The Open University is incorporated by Royal Charter (RC 000391), an exempt
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