drm/i915: Add tracepoints

By adding tracepoint equivalents for WATCH_BUF/EXEC we are able to monitor
the lifetimes of objects, requests and significant events. These events can
then be probed using the tracing frameworks, such as systemtap and, in
particular, perf.

For example to record the stack trace for every GPU stall during a run, use

  $ perf record -e i915:i915_gem_request_wait_begin -c 1 -g

And

  $ perf report

to view the results.

[Updated to fix compilation issues caused.]
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Ben Gamari <bgamari@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 59826c5b8760..ae7ec0390024 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -33,6 +33,7 @@
 #include "intel_drv.h"
 #include "i915_drm.h"
 #include "i915_drv.h"
+#include "i915_trace.h"
 
 /* Really want an OS-independent resettable timer.  Would like to have
  * this loop run for (eg) 3 sec, but have the timer reset every time
@@ -49,14 +50,18 @@ int i915_wait_ring(struct drm_device * dev, int n, const char *caller)
         u32 last_head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
         int i;
 
+        trace_i915_ring_wait_begin (dev);
+
         for (i = 0; i < 100000; i++) {
                 ring->head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
                 acthd = I915_READ(acthd_reg);
                 ring->space = ring->head - (ring->tail + 8);
                 if (ring->space < 0)
                         ring->space += ring->Size;
-                if (ring->space >= n)
+                if (ring->space >= n) {
+                        trace_i915_ring_wait_end (dev);
                         return 0;
+                }
 
                 if (dev->primary->master) {
                         struct drm_i915_master_private *master_priv = dev->primary->master->driver_priv;
@@ -76,6 +81,7 @@ int i915_wait_ring(struct drm_device * dev, int n, const char *caller)
 
         }
 
+        trace_i915_ring_wait_end (dev);
         return -EBUSY;
 }