Re: [PATCH] drm/i915: Don't continually defer the hangcheck

Mika Kuoppala
2014-11-19T10:44:21Z

Chris Wilson <chris@chris-wilson.co.uk> writes:

> With multiple rings, we may continue to render on the blitter whilst
> executing an infinite shader on the render ring. As we currently, rearm
> the timer with each execbuf, in this scenario the hangcheck will never
> fire and we will never detect the lockup on the render ring. Instead,
> only arm the timer once per hangcheck, so that hangcheck runs more
> frequently.
>
> v2: Rearrange code to avoid triggering a BUG_ON in add_timer from
> softirq context.
>
> Testcase: igt/gem_reset_stats/defer-hangcheck*
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86225
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@intel.com>
> ---

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

> drivers/gpu/drm/i915/i915_irq.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 729e9a329f76..c88c005433d6 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -988,7 +988,6 @@ static void notify_ring(struct drm_device *dev,
> trace_i915_gem_request_complete(ring);
>
> wake_up_all(&ring->irq_queue);
> - i915_queue_hangcheck(dev);
> }
>
> static u32 vlv_c0_residency(struct drm_i915_private *dev_priv,
> @@ -3035,11 +3034,15 @@ static void i915_hangcheck_elapsed(unsigned long data)
> void i915_queue_hangcheck(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> + struct timer_list *timer = &dev_priv->gpu_error.hangcheck_timer;
> +
> if (!i915.enable_hangcheck)
> return;
>
> - mod_timer(&dev_priv->gpu_error.hangcheck_timer,
> - round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
> + /* Don't continually defer the hangcheck, but make sure it is active */
> + if (!timer_pending(timer))
> + timer->expires = round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES);
> + mod_timer(timer, timer->expires);
> }
>
> static void ibx_irq_reset(struct drm_device *dev)
> --
> 2.1.3
>
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