From: Tejun Heo <tj@kernel.org>
To: "Michel Dänzer" <michel@daenzer.net>
Cc: "Alex Deucher" <alexander.deucher@amd.com>,
"Bhaktipriya Shridhar" <bhaktipriya96@gmail.com>,
"Christian König" <christian.koenig@amd.com>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/radeon: Remove deprecated create_singlethread_workqueue
Date: Tue, 12 Jul 2016 13:52:52 -0400 [thread overview]
Message-ID: <20160712175252.GN3190@htj.duckdns.org> (raw)
In-Reply-To: <7f4299b1-a118-50ce-1f40-fbcfdfb19942@daenzer.net>
Hello,
On Fri, Jul 08, 2016 at 02:52:30PM +0900, Michel Dänzer wrote:
> On 07.07.2016 16:43, Christian König wrote:
> >>> 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.
> >
> > Well to be precise with a typical 1920x1080@60 resolution you have about
> > 2.16ms time under ideal conditions for the flip.
> >
> > So using the high priority queue still sounds like a good idea to me.
>
> How did you arrive at 2.16ms?
>
> Userspace can call the ioctl up to one full refresh cycle ahead of time,
> which is ~16ms at 60 Hz. On the other hand userspace can also call the
> ioctl arbitrarily close to the vertical blank period, in which case even
> a delay of just 1ms (or even significantly less) may cause the flip to
> be delayed by one refresh cycle.
If there's too long a delay, the outcome is missing the refresh cycle,
right? Hmmm... yeah, WQ_HIGHPRI probably is the right answer here.
Bhaktipriya, can you please update the patch to use a dedicated
workqueue with WQ_HIGHPRI?
Thanks.
--
tejun
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next prev parent reply other threads:[~2016-07-12 17:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-02 11:03 [PATCH] drm/radeon: Remove deprecated create_singlethread_workqueue Bhaktipriya Shridhar
2016-07-02 13:46 ` Tejun Heo
2016-07-04 3:58 ` Michel Dänzer
2016-07-05 21:06 ` Tejun Heo
2016-07-06 3:12 ` Michel Dänzer
2016-07-06 13:45 ` Tejun Heo
2016-07-07 3:32 ` Michel Dänzer
2016-07-07 7:43 ` Christian König
2016-07-08 5:52 ` Michel Dänzer
2016-07-12 17:52 ` Tejun Heo [this message]
2016-07-16 11:30 ` [PATCH v2] " Bhaktipriya Shridhar
2016-07-18 13:21 ` Christian König
2016-07-19 0:48 ` Tejun Heo
2016-07-28 16:14 ` Alex Deucher
-- strict thread matches above, loose matches on Subject: below --
2016-06-28 17:26 [PATCH] " Bhaktipriya Shridhar
2016-06-28 17:44 ` Bhaktipriya Shridhar
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