linux-kernel - Re: [PATCH v7 0/6] V4L2 Explicit Synchronization

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Message-ID: <20180110171156.GC3530@jade>
Date:   Wed, 10 Jan 2018 15:11:56 -0200
From:   Gustavo Padovan <gustavo@...ovan.org>
To:     Nicolas Dufresne <nicolas@...fresne.ca>
Cc:     linux-media@...r.kernel.org, Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@....samsung.com>,
        Shuah Khan <shuahkh@....samsung.com>,
        Pawel Osciak <pawel@...iak.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Sakari Ailus <sakari.ailus@....fi>,
        Brian Starkey <brian.starkey@....com>,
        Thierry Escande <thierry.escande@...labora.com>,
        linux-kernel@...r.kernel.org,
        Gustavo Padovan <gustavo.padovan@...labora.com>
Subject: Re: [PATCH v7 0/6] V4L2 Explicit Synchronization

2018-01-10 Nicolas Dufresne <nicolas@...fresne.ca>:

> Le mercredi 10 janvier 2018 à 14:07 -0200, Gustavo Padovan a écrit :
> > v7 bring a fix for a crash when not using fences and a uAPI fix.
> > I've done a bit more of testing on it and also measured some
> > performance. On a intel laptop a DRM<->V4L2 pipeline with fences is
> > runnning twice as faster than the same pipeline with no fences.
> 
> What does it mean twice faster here ?

That capture then display on the screen for a given number of frames was
completing in about half of the time when using fences and passing then
to the other driver right away when they are received.

Gustavo