diff mbox

[09/13] drm/i915: Add a tracepoint for using a semaphore

Message ID 1379968410-14428-10-git-send-email-rodrigo.vivi@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Rodrigo Vivi Sept. 23, 2013, 8:33 p.m. UTC 
From: Chris Wilson <chris@chris-wilson.co.uk>

So that we can find the callers who introduce a ring stall. A single
ring stall is not too unwelcome, the right issue becomes when they start
to interlock and prevent any concurrent work. That, however, is a little
tricker to detect with a mere tracepoint!

v2: Rebrand it as a ring event, rather than an object event.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
---
 drivers/gpu/drm/i915/i915_gem.c   |  2 ++
 drivers/gpu/drm/i915/i915_trace.h | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)

Comments

Ville Syrjälä Sept. 25, 2013, 9:34 a.m. UTC | #1 
On Mon, Sep 23, 2013 at 05:33:26PM -0300, Rodrigo Vivi wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> So that we can find the callers who introduce a ring stall. A single
> ring stall is not too unwelcome, the right issue becomes when they start
> to interlock and prevent any concurrent work. That, however, is a little
> tricker to detect with a mere tracepoint!
> 
> v2: Rebrand it as a ring event, rather than an object event.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>

Just wondering if we would want to see the seqno(s) in the trace as well?

But anyway, the patch looks fine.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_gem.c   |  2 ++
>  drivers/gpu/drm/i915/i915_trace.h | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index d68cc5c..4a16491 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2614,6 +2614,8 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
>  	if (ret)
>  		return ret;
>  
> +	trace_i915_gem_ring_sync_to(from, to);
> +
>  	ret = to->sync_to(to, from, seqno);
>  	if (!ret)
>  		/* We use last_read_seqno because sync_to()
> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> index 5c8e36a..48e8f07 100644
> --- a/drivers/gpu/drm/i915/i915_trace.h
> +++ b/drivers/gpu/drm/i915/i915_trace.h
> @@ -233,6 +233,25 @@ TRACE_EVENT(i915_gem_evict_everything,
>  	    TP_printk("dev=%d", __entry->dev)
>  );
>  
> +TRACE_EVENT(i915_gem_ring_sync_to,
> +	    TP_PROTO(struct intel_ring_buffer *from, struct intel_ring_buffer *to),
> +	    TP_ARGS(from, to),
> +
> +	    TP_STRUCT__entry(
> +			     __field(u32, dev)
> +			     __field(u32, sync_from)
> +			     __field(u32, sync_to)
> +			     ),
> +
> +	    TP_fast_assign(
> +			   __entry->dev = from->dev->primary->index;
> +			   __entry->sync_from = from->id;
> +			   __entry->sync_to = to->id;
> +			   ),
> +
> +	    TP_printk("dev=%u, sync-from=%u, sync-to=%u", __entry->dev, __entry->sync_from, __entry->sync_to)
> +);
> +
>  TRACE_EVENT(i915_gem_ring_dispatch,
>  	    TP_PROTO(struct intel_ring_buffer *ring, u32 flags),
>  	    TP_ARGS(ring, flags),
> -- 
> 1.8.1.4
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Daniel Vetter Sept. 25, 2013, 10:11 a.m. UTC | #2 
On Wed, Sep 25, 2013 at 12:34:37PM +0300, Ville Syrjälä wrote:
> On Mon, Sep 23, 2013 at 05:33:26PM -0300, Rodrigo Vivi wrote:
> > From: Chris Wilson <chris@chris-wilson.co.uk>
> > 
> > So that we can find the callers who introduce a ring stall. A single
> > ring stall is not too unwelcome, the right issue becomes when they start
> > to interlock and prevent any concurrent work. That, however, is a little
> > tricker to detect with a mere tracepoint!
> > 
> > v2: Rebrand it as a ring event, rather than an object event.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> 
> Just wondering if we would want to see the seqno(s) in the trace as well?

Hm yeah, I guess the seqno we're syncing on the from ring would be useful
to gauge how much parallelism there really is. Chris, care to respin?
-Daniel

> 
> But anyway, the patch looks fine.
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> > ---
> >  drivers/gpu/drm/i915/i915_gem.c   |  2 ++
> >  drivers/gpu/drm/i915/i915_trace.h | 19 +++++++++++++++++++
> >  2 files changed, 21 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index d68cc5c..4a16491 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -2614,6 +2614,8 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
> >  	if (ret)
> >  		return ret;
> >  
> > +	trace_i915_gem_ring_sync_to(from, to);
> > +
> >  	ret = to->sync_to(to, from, seqno);
> >  	if (!ret)
> >  		/* We use last_read_seqno because sync_to()
> > diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> > index 5c8e36a..48e8f07 100644
> > --- a/drivers/gpu/drm/i915/i915_trace.h
> > +++ b/drivers/gpu/drm/i915/i915_trace.h
> > @@ -233,6 +233,25 @@ TRACE_EVENT(i915_gem_evict_everything,
> >  	    TP_printk("dev=%d", __entry->dev)
> >  );
> >  
> > +TRACE_EVENT(i915_gem_ring_sync_to,
> > +	    TP_PROTO(struct intel_ring_buffer *from, struct intel_ring_buffer *to),
> > +	    TP_ARGS(from, to),
> > +
> > +	    TP_STRUCT__entry(
> > +			     __field(u32, dev)
> > +			     __field(u32, sync_from)
> > +			     __field(u32, sync_to)
> > +			     ),
> > +
> > +	    TP_fast_assign(
> > +			   __entry->dev = from->dev->primary->index;
> > +			   __entry->sync_from = from->id;
> > +			   __entry->sync_to = to->id;
> > +			   ),
> > +
> > +	    TP_printk("dev=%u, sync-from=%u, sync-to=%u", __entry->dev, __entry->sync_from, __entry->sync_to)
> > +);
> > +
> >  TRACE_EVENT(i915_gem_ring_dispatch,
> >  	    TP_PROTO(struct intel_ring_buffer *ring, u32 flags),
> >  	    TP_ARGS(ring, flags),
> > -- 
> > 1.8.1.4
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d68cc5c..4a16491 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2614,6 +2614,8 @@  i915_gem_object_sync(struct drm_i915_gem_object *obj,
 	if (ret)
 		return ret;
 
+	trace_i915_gem_ring_sync_to(from, to);
+
 	ret = to->sync_to(to, from, seqno);
 	if (!ret)
 		/* We use last_read_seqno because sync_to()
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 5c8e36a..48e8f07 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -233,6 +233,25 @@  TRACE_EVENT(i915_gem_evict_everything,
 	    TP_printk("dev=%d", __entry->dev)
 );
 
+TRACE_EVENT(i915_gem_ring_sync_to,
+	    TP_PROTO(struct intel_ring_buffer *from, struct intel_ring_buffer *to),
+	    TP_ARGS(from, to),
+
+	    TP_STRUCT__entry(
+			     __field(u32, dev)
+			     __field(u32, sync_from)
+			     __field(u32, sync_to)
+			     ),
+
+	    TP_fast_assign(
+			   __entry->dev = from->dev->primary->index;
+			   __entry->sync_from = from->id;
+			   __entry->sync_to = to->id;
+			   ),
+
+	    TP_printk("dev=%u, sync-from=%u, sync-to=%u", __entry->dev, __entry->sync_from, __entry->sync_to)
+);
+
 TRACE_EVENT(i915_gem_ring_dispatch,
 	    TP_PROTO(struct intel_ring_buffer *ring, u32 flags),
 	    TP_ARGS(ring, flags),