[Intel-gfx] [PATCH v2 1/6] drm/i915: Lock out execlist tasklet while peeking inside for busy-stats

[Chris Wilson]

Quoting Mika Kuoppala (2018-01-17 13:22:09)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > In order to prevent a race condition where we may end up overaccounting
> > the active state and leaving the busy-stats believing the GPU is 100%
> > busy, lock out the tasklet while we reconstruct the busy state. There is
> > no direct spinlock guard for the execlists->port[], so we need to
> > utilise tasklet_disable() as a synchronous barrier to prevent the only
> > writer to execlists->port[] from running at the same time as the enable.
> >
> > Fixes: 4900727d35bb ("drm/i915/pmu: Reconstruct active state on starting busy-stats")
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> This series applied on drm-tip with j1900. Uptime 2h 35min until system
> hang. Load was glxgears + video.

Same load (the good old bug.sh), currently 48 hours. As stable as
skip_hw_write here. :|

Can you give the full series with the pcu_lock refactoring a whirl?
-Chris