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

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Date:   Wed, 4 Sep 2019 08:53:25 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Feng Tang <feng.tang@...el.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Rong Chen <rong.a.chen@...el.com>, michel@...nzer.net,
        linux-kernel@...r.kernel.org,
        dri-devel <dri-devel@...ts.freedesktop.org>, lkp@...org
Subject: Re: [LKP] [drm/mgag200] 90f479ae51: vm-scalability.median -18.8%
 regression

Hi

Am 04.09.19 um 08:27 schrieb Feng Tang:
>> 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?

To my knowledge, there's only one instance of the worker. Re-scheduling
the worker before a previous instance started, will not create a second
instance. The worker's instance will complete all pending updates. So in
some way, skipping workers already happens.

Best regards
Thomas

> 
> Thanks,
> Feng
> 
>>
>> Best regards
>> Thomas
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

-- 
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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