Hi Thomas,
On Mon, Sep 09, 2019 at 04:12:37PM +0200, Thomas Zimmermann wrote:
> Hi
>
> Am 04.09.19 um 08:27 schrieb Feng Tang:
> > Hi Thomas,
> >
> > On Wed, Aug 28, 2019 at 12:51:40PM +0200, Thomas Zimmermann wrote:
> >> 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.
> >
> > Thanks for the detailed info, so the original code skips time-consuming
> > work inside atomic context on purpose. Is there any space to optmise it?
> > If 2 scheduled update worker are handled at almost same time, can one be
> > skipped?
>
> We discussed ideas on IRC and decided that screen updates could be
> synchronized with vblank intervals. This may give some rate limiting to
> the output.
>
> If you like, you could try the patch set at [1]. It adds the respective
> code to console and mgag200.
I just tried the 2 patches, no obvious change (comparing to the
18.8% regression), both in overall benchmark and micro-profiling.
90f479ae51afa45e 04a0983095feaee022cdd65e3e4
---------------- ---------------------------
37236 ± 3% +2.5% 38167 ± 3% vm-scalability.median
0.15 ± 24% -25.1% 0.11 ± 23% vm-scalability.median_stddev
0.15 ± 23% -25.1% 0.11 ± 22% vm-scalability.stddev
12767318 ± 4% +2.5% 13089177 ± 3% vm-scalability.throughput
Thanks,
Feng
>
> Best regards
> Thomas
>
> [1]
> https://lists.freedesktop.org/archives/dri-devel/2019-September/234850.html
>
> >
> > Thanks,
> > Feng
> >
> >>
> >> Best regards
> >> Thomas
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
> HRB 21284 (AG Nürnberg)
>
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