Re: [PATCH 2/5] drm/i915: Add a tracepoint for the shrinker

Daniel Vetter
2015-10-06T12:51:32Z

On Thu, Oct 01, 2015 at 12:18:26PM +0100, Chris Wilson wrote:
> Often it is very useful to know why we suddenly purge vast tracts of
> memory and surprisingly up until now we didn't even have a tracepoint
> for when we shrink our memory.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_gem_shrinker.c | 2 ++
> drivers/gpu/drm/i915/i915_trace.h | 20 ++++++++++++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> index b627d07fad29..88f66a2586ec 100644
> --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
> +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> @@ -85,6 +85,8 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
> }, *phase;
> unsigned long count = 0;
>
> + trace_i915_gem_shrink(dev_priv, target, flags);

Shouldn't we also dump how many pages we actually managed to shrink, i.e.
count (at the end of the functions).

Also we have a slab_start/end tracepoint already, but that one obviously
doesn't cover the internal calls to i915_gem_shrink. Should imo be
mentioned in the commit message.
-Daniel

> +
> /*
> * As we may completely rewrite the (un)bound list whilst unbinding
> * (due to retiring requests) we have to strictly process only
> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> index e6b5c7470ba0..ed7f42f2e740 100644
> --- a/drivers/gpu/drm/i915/i915_trace.h
> +++ b/drivers/gpu/drm/i915/i915_trace.h
> @@ -107,6 +107,26 @@ TRACE_EVENT(i915_gem_object_create,
> TP_printk("obj=%p, size=%u", __entry->obj, __entry->size)
> );
>
> +TRACE_EVENT(i915_gem_shrink,
> + TP_PROTO(struct drm_i915_private *i915, unsigned long target, unsigned flags),
> + TP_ARGS(i915, target, flags),
> +
> + TP_STRUCT__entry(
> + __field(int, dev)
> + __field(unsigned long, target)
> + __field(unsigned, flags)
> + ),
> +
> + TP_fast_assign(
> + __entry->dev = i915->dev->primary->index;
> + __entry->target = target;
> + __entry->flags = flags;
> + ),
> +
> + TP_printk("dev=%d, target=%lu, flags=%x",
> + __entry->dev, __entry->target, __entry->flags)
> +);
> +
> TRACE_EVENT(i915_vma_bind,
> TP_PROTO(struct i915_vma *vma, unsigned flags),
> TP_ARGS(vma, flags),
> --
> 2.6.0
>
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--
Daniel Vetter
Software Engineer, Intel Corporation