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Re: [PATCH] drm/radeon: Remove deprecated create_singlethread_workqueue

From Michel Dänzer <michel@daenzer.net>
Newsgroups linux.kernel
Subject Re: [PATCH] drm/radeon: Remove deprecated create_singlethread_workqueue
Date 2016-07-07 06:20 +0200
Message-ID <rS8X8-1QG-3@gated-at.bofh.it> (permalink)
References (1 earlier) <rQtt0-4cj-3@gated-at.bofh.it> <rR3d7-zy-5@gated-at.bofh.it> <rRFLs-8bM-23@gated-at.bofh.it> <rRLxv-3L0-1@gated-at.bofh.it> <rRVnc-1pJ-19@gated-at.bofh.it>
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On 06.07.2016 22:45, Tejun Heo wrote:
> On Wed, Jul 06, 2016 at 12:12:52PM +0900, Michel Dänzer wrote:
> 
>> Not being very familiar with the workqueue APIs, I'll describe how it's
>> supposed to work from a driver POV, which will hopefully help you guys
>> decide on the most appropriate alloc_workqueue parameters.
>>
>> There is one flip work queue for each hardware CRTC. At most one
>> radeon_flip_work_func item can be queued for any of them at any time.
>> When a radeon_flip_work_func item is queued, it should be executed ASAP
>> (so WQ_HIGHPRI might be appropriate?).
> 
> Hmmm... the only time WQ_HIGHPRI should be used is when it'd otherwise
> require a kthread w/ nice value at -20.  Would that be the case here?
> What are the consequences of the work item getting delayed?

A page flip may be delayed to a later display refresh cycle.


> Also, what kind of delays matter here?  Is it millisec range or micro?

It can be the latter in theory, but normally rather the former.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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[PATCH] drm/radeon: Remove deprecated create_singlethread_workqueue Bhaktipriya Shridhar <bhaktipriya96@gmail.com> - 2016-07-02 13:10 +0200
  Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Tejun Heo <tj@kernel.org> - 2016-07-02 15:50 +0200
    Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Michel Dänzer <michel@daenzer.net> - 2016-07-04 06:00 +0200
      Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Tejun Heo <tj@kernel.org> - 2016-07-05 23:10 +0200
        Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Michel Dänzer <michel@daenzer.net> - 2016-07-06 05:20 +0200
          Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Tejun Heo <tj@kernel.org> - 2016-07-06 15:50 +0200
            Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Michel Dänzer <michel@daenzer.net> - 2016-07-07 06:20 +0200
              Re: [PATCH] drm/radeon: Remove deprecated  create_singlethread_workqueue Michel Dänzer <michel@daenzer.net> - 2016-07-08 08:00 +0200

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