[Intel-gfx] Interrupt latency on some 945GM platforms

[Shaohua Li]

2010/9/26 Stefan Biereigel <security at biereigel-wb.de>:
>  Am 24.09.2010 21:51, schrieb Jesse Barnes:
>>
>> On Fri, 24 Sep 2010 22:48:36 +0300
>> Vasily Khoruzhick<anarsoul at gmail.com>  wrote:
>>
>>> On 24 of September 2010 22:39:01 Jesse Barnes wrote:
>>>>
>>>> On Thu, 16 Sep 2010 23:06:46 +0300
>>>>
>>>> Vasily Khoruzhick<anarsoul at gmail.com>  wrote:
>>>>>
>>>>> В сообщении от 16 of September 2010 21:50:50 автор Thomas Gleixner
>>>
>>> написал:
>>>>>>
>>>>>> Ok. The problematic part of HPET was not the clocksource, it was the
>>>>>> clock event device which failed to deliver interrupts occasionally. It
>>>>>> was worth a try at least.
>>>>>
>>>>> Hm, it seems that jerky glxgears is not related to jerky keyboard
>>>>> events.
>>>>> Keyboard is jerky only in konsole (kde terminal emulator), it seems
>>>>> something happened it seems that font rendering performance is much
>>>>> worse in latest xf86-video-intel than in xf86-video-intel-2.12.0.
>>>>
>>>> Len just had me try a few things too:
>>>>   - maxcpus=1 lets things work
>>>>   - offlining cpu1 at runtime (echo 0
>>>>
>>>>     >  /sys/devices/system/cpu/cpu1/online) lets things work
>>>>
>>>>   - binding the i915 interrupt to cpu 0 does *not* help
>>>>
>>>> Vasily and Paolo, do you both have Atom CPUs with hyperthreading
>>>> enabled?
>>>
>>> Nope, I have Core2Duo T5500, dual-core, no hyperthreading :)
>>
>> Hm, well there goes the theory about Atom HT...
>>
>
> Hello Everyone,
> just to add on to reports of this problem, there was a Thread here in LKML
> some months ago targeting the same problem (but not really attacking it at
> the Chipset driver). As I have one of those Laptops with a 945GM-Chipset and
> am stuck with the same Problem (disabled tickless now as a workaround and
> set ticks to 1000) I could maybe do some testing of patches.
> So what I can summarize is what the others did before: Disabling CPU1 helps,
> adding nohz=off helps, changing the Clocksource afterwards helps, binding
> the Interrupt does NOT help.
> So here's the Link to the old Discussion with follow-ups, maybe you can get
> some furter information from there.
> http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-05/msg03696.html
> We targeted the BIOS itself as everyone in this thread happened to own an
> Phoenix BIOS with some special version string.
> best, Stefan
does disable msi help with 'pci=nomsi'?