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Date: Wed, 23 Jul 2014 11:30:44 +0200
Message-ID: <CAKMK7uEowhvc+4Jc6t2NAeE1joFaohJ6cP7sU-Akut6b3ta=1g@mail.gmail.com>
Subject: Re: [Nouveau] [PATCH 09/17] drm/radeon: use common fence
 implementation for fences
From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Cc: =?UTF-8?Q?Christian_K=C3=B6nig?= <deathsimple@vodafone.de>,
        Maarten Lankhorst <maarten.lankhorst@canonical.com>,
        Thomas Hellstrom <thellstrom@vmware.com>,
        nouveau <nouveau@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Ben Skeggs <bskeggs@redhat.com>,
        "Deucher, Alexander" <alexander.deucher@amd.com>
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Sender: linux-kernel-owner@vger.kernel.org

On Wed, Jul 23, 2014 at 11:27 AM, Christian König
<christian.koenig@amd.com> wrote:
> You submit a job to the hardware and then block the job to wait for radeon
> to be finished? Well than this would indeed require a hardware reset, but
> wouldn't that make the whole problem even worse?
>
> I mean currently we block one userspace process to wait for other hardware
> to be finished with a buffer, but what you are describing here blocks the
> whole hardware to wait for other hardware which in the end blocks all
> userspace process accessing the hardware.

There is nothing new here with prime - if one context hangs the gpu it
blocks everyone else on i915.

> Talking about alternative approaches wouldn't it be simpler to just offload
> the waiting to a different kernel or userspace thread?

Well this is exactly what we'll do once we have the scheduler. But
this is an orthogonal issue imo.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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