Re: [LKP] [drm/mgag200] 90f479ae51: vm-scalability.median -18.8% regression

[Thomas Zimmermann]

Hi

Am 28.08.19 um 11:37 schrieb Rong Chen:
> Hi Thomas,
> 
> On 8/28/19 1:16 AM, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 27.08.19 um 14:33 schrieb Chen, Rong A:
>>> Both patches have little impact on the performance from our side.
>> Thanks for testing. Too bad they doesn't solve the issue.
>>
>> There's another patch attached. Could you please tests this as well?
>> Thanks a lot!
>>
>> The patch comes from Daniel Vetter after discussing the problem on IRC.
>> The idea of the patch is that the old mgag200 code might display much
>> less frames that the generic code, because mgag200 only prints from
>> non-atomic context. If we simulate this with the generic code, we should
>> see roughly the original performance.
>>
>>
> 
> It's cool, the patch "usecansleep.patch" can fix the issue.

Thank you for testing. But don't get too excited, because the patch
simulates a bug that was present in the original mgag200 code. A
significant number of frames are simply skipped. That is apparently the
reason why it's faster.

Best regards
Thomas

> commit:
> Â f1f8555dfb9 drm/bochs: Use shadow buffer for bochs framebuffer console
> Â 90f479ae51a drm/mgag200: Replace struct mga_fbdev with generic
> framebuffer emulation
> Â b976b04c2bc only schedule worker from non-atomic context
> 
> f1f8555dfb9a70a2Â 90f479ae51afa45efab97afdde b976b04c2bcf33148d6c7bc1a2Â
> testcase/testparams/testbox
> ----------------Â -------------------------- --------------------------Â
> ---------------------------
> ÂÂÂÂÂÂÂÂ %stddevÂÂÂÂÂ changeÂÂÂÂÂÂÂÂ %stddevÂÂÂÂÂ change %stddev
> ÂÂÂÂÂÂÂÂÂÂÂÂ \ÂÂÂÂÂÂÂÂÂ |ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ \ÂÂÂÂÂÂÂÂÂ | \
> ÂÂÂÂ 42912ÂÂÂÂÂÂÂÂÂÂÂÂ -15%ÂÂÂÂÂ 36517 44093
> vm-scalability/performance-300s-8T-anon-cow-seq-hugetlb/lkp-knm01
> ÂÂÂÂ 42912ÂÂÂÂÂÂÂÂÂÂÂÂ -15%ÂÂÂÂÂ 36517 44093ÂÂÂÂÂÂÂ GEO-MEAN
> vm-scalability.median
> 
> Best Regards,
> Rong Chen
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-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix ImendÃrffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG NÃrnberg)

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