On Fri, 18 Mar 2011 18:12:25 +0000
Chris Wilson <ch...@chris-wilson.co.uk> wrote:
> On Fri, 18 Mar 2011 10:56:15 -0700, Jesse Barnes <jbar...@virtuousgeek.org>
> wrote:
> > Add trace points for when the GPU goes from idle to busy and vice-versa.
> > Also trace when we start to idle the GPU and when it finally does idle
> > (this could take awhile if the ring is full of commands).
> >
> > Signed-off-by: Jesse Barnes <jbar...@virtuousgeek.org>
> > ---
> > drivers/gpu/drm/i915/i915_drv.h | 4 +++
> > drivers/gpu/drm/i915/i915_gem.c | 4 +++
> > drivers/gpu/drm/i915/i915_irq.c | 5 ++++
> > drivers/gpu/drm/i915/i915_trace.h | 35
> > +++++++++++++++++++++++++++++++
> > drivers/gpu/drm/i915/intel_ringbuffer.c | 6 +++++
> > 5 files changed, 54 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > b/drivers/gpu/drm/i915/i915_drv.h
> > index c8a21ce..adff483 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -674,6 +674,10 @@ typedef struct drm_i915_private {
> > int lvds_downclock;
> > struct work_struct idle_work;
> > struct timer_list idle_timer;
> > +
> > + bool gpu_busy;
> > + unsigned long gpu_busy_start;
> > +
> > bool busy;
> > u16 orig_clock;
> > int child_dev_num;
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c
> > b/drivers/gpu/drm/i915/i915_gem.c
> > index ac23dcf..18534d7 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -2208,6 +2208,8 @@ i915_gpu_idle(struct drm_device *dev)
> > bool lists_empty;
> > int ret, i;
> >
> > + trace_i915_gpu_idle_start(dev);
> > +
> > lists_empty = (list_empty(&dev_priv->mm.flushing_list) &&
> > list_empty(&dev_priv->mm.active_list));
> > if (lists_empty)
> > @@ -2220,6 +2222,8 @@ i915_gpu_idle(struct drm_device *dev)
> > return ret;
> > }
> >
> > + trace_i915_gpu_idle_end(dev);
> > +
> > return 0;
> > }
> >
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > b/drivers/gpu/drm/i915/i915_irq.c
> > index 346dd85..0d3cc62 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -365,6 +365,11 @@ static void notify_ring(struct drm_device *dev,
> > dev_priv->hangcheck_count = 0;
> > mod_timer(&dev_priv->hangcheck_timer,
> > jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
> > +
> > + if (I915_READ_HEAD(ring) == I915_READ_TAIL(ring)) {
> > + dev_priv->gpu_busy = false;
> > + trace_i915_gpu_busy_end(dev_priv->dev);
> > + }
> > }
>
> IRQ notifies should in fact be few and far between. I do not see how you
> actually detect when the gpu goes idle should we not be waiting on a
> request. So I think you need a pair of ring->irq_get/irq_put in and add
> tracepoints for each ring as opposed to device! You can then have a device
> busy which is the summation of active rings...
Oops, yeah I have a hack in my local tree that disables irq_put so I
get a notify every time. We only want that if tracing is enabled
though (even then it will make things a lot noisier and affect CPU
utilization, but I guess totally invisible tracing isn't really
possible).
Would probably be better to have trace points per ring to track busy
idle for each. I'll fix it up.
--
Jesse Barnes, Intel Open Source Technology Center
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