Re: kmemleak, cpu usage jump out of nowhere

[Pekka Enberg]

On Wed, Jul 14, 2010 at 11:54 AM, Zeno Davatz <zdavatz@xxxxxxxxx> wrote:
> On Wed, Jul 14, 2010 at 10:38 AM, Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
>> Zeno Davatz wrote:
>>>
>>> On Wed, Jul 14, 2010 at 10:31 AM, Damien Wyart <damien.wyart@xxxxxxx>
>>> wrote:
>>>
>>>>> On Wed, Jul 14, 2010 at 9:12 AM, Zeno Davatz <zdavatz@xxxxxxxxx> wrote:
>>>>>>
>>>>>> I got a new Intel core-8 i7 processor.
>>>>>> I am on kernel uname -a
>>>>>> Linux zenogentoo 2.6.35-rc5 #97 SMP Tue Jul 13 16:13:25 CEST 2010 i686
>>>>>> Intel(R) Core(TM) i7 CPU 960 @ 3.20GHz GenuineIntel GNU/Linux
>>>>>> Sometimes in the middle of nowhere all of a sudden all of my 8-cores
>>>>>> are at 100% CPU usage and my machine really lags and hangs and is not
>>>>>> useable anymore. Some random process just grabs a bunch CPUs according
>>>>>> to htop.
>>>>
>>>> * Pekka Enberg <penberg@xxxxxxxxxxxxxx> [2010-07-14 11:05]:
>>>>>
>>>>> Why did you enable CONFIG_DEBUG_KMEMLEAK? Memory leak scanning is
>>>>> likely the source of these pauses.
>>>>
>>>> I am seeing the same problem with a Core i7 920 and 2.6.35-rc5, and I do
>>>> not have CONFIG_DEBUG_KMEMLEAK enabled, so I think this is not related.
>>>>
>>>> I do not see anything special in the logs, just the load becoming mad
>>>> and almost preventing ssh access. I've been seeing that since the first
>>>> 2.6.35 rc I tested (-rc2 or -rc3, I don't remember) and I did not have
>>>> time to report it before but I was surprised nobody else did. No problem
>>>> with 2.6.34 and 2.6.34.1.
>>>
>>> same with me. My last build I tested was 2.6.34-rc7. No problems
>>> there. No CPU jumps out of nowhere.
>>>
>>> It is like any application all of a sudden use 400% CPU i.e. htop.
>>
>> Interesting. Lets CC some scheduler folks for help.
>
> Once it is gdm, once it is firefox-bin once it is htop. Its really od.
> Nothing crashes one of those just uses lots of CPU. The machine just
> gets really slow and then calms down again and everything is back to
> normal.

That's the part that makes me think it's scheduler and/or cpufreq related.

> ;)
>
> Maybe a bad temper?

Yeah, maybe Tux is having a bad day. :-)
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