Re: [PATCH] drm/radeon/kms: fence cleanup + more reliable GPU lockup detection

[Alan Swanson <swanson@ukfsn.org>]

On Fri, 2010-02-26 at 15:49 +0100, Jerome Glisse wrote:
> This patch cleanup the fence code, it drops the timeout field of
> fence as the time to complete each IB is unpredictable and shouldn't
> be bound.
> 
> The fence cleanup lead to GPU lockup detection improvement, this
> patch introduce a callback, allowing to do asic specific test for
> lockup detection. In this patch the CP is use as a first indicator
> of GPU lockup. If CP doesn't make progress during 1second we assume
> we are facing a GPU lockup.
> 
> To avoid overhead of testing GPU lockup frequently due to fence
> taking time to be signaled we query the lockup callback every
> 100msec. There is plenty code comment explaining the design & choise
> inside the code.

Every 100msec? Is this running all the time? If so, that's not very good
for CPU power saving to lower C-states in an idle system. We could at
least use one of the round_jiffies.

> This have been tested mostly on R3XX/R5XX hw, in normal running
> destkop (compiz firefox, quake3 running) the lockup callback wasn't
> call once (1 hour session). Also tested with forcing GPU lockup and
> lockup was reported after the 1s CP activity timeout.
> 
> Signed-off-by: Jerome Glisse <jglisse@redhat.com>

-- 
Alan.

"One must never be purposelessnessnesslessness."


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