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

[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.

commit:
 f1f8555dfb9 drm/bochs: Use shadow buffer for bochs framebuffer console
 90f479ae51a drm/mgag200: Replace struct mga_fbdev with generic 
framebuffer emulation
 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