Re: [Nouveau] [PATCH 09/17] drm/radeon: use common fence implementation for fences

Maarten Lankhorst
2014-07-23T09:38:34Z

op 23-07-14 11:36, Christian König schreef:
> Am 23.07.2014 11:30, schrieb Daniel Vetter:
>> 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.
>
> Mhm, could have the scheduler first?
>
> Cause that sounds like reducing the necessary fence interface to just a fence->wait function.
You would also lose benefits like having a 'perf timechart' for gpu's.

~Maarten