[sysprof] sources/perf: Disable the broken i915 tracepoints for now.

[Christian Hergert <chergert src gnome org>]

commit 23a0cebfe2f2e55aa10e27b446a36e2e88b5dc71
Author: Eric Anholt <eric anholt net>
Date:   Thu May 17 14:46:51 2018 +0100

    sources/perf: Disable the broken i915 tracepoints for now.
    
    I need to build a new kernel and test the tracepoints, but disable
    these for the moment to prevent people from getting surprising garbage
    timelines.

 lib/sources/sp-perf-source.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)
---
diff --git a/lib/sources/sp-perf-source.c b/lib/sources/sp-perf-source.c
index 3bdc722..08c2cba 100644
--- a/lib/sources/sp-perf-source.c
+++ b/lib/sources/sp-perf-source.c
@@ -85,17 +85,15 @@ static const SpOptionalTracepoint optional_tracepoints[] = {
 
   /* I915 GPU execution.
    *
-   * I don't know i915's model too well any more, but I think while
-   * there's an add that hasn't been retired (use the ring and seqno
-   * to correlate them, I think), then the GPU is busy.  The retires
-   * may or may not be delayed a while if the CPU isn't currently
-   * blocking on the GPU -- I would think you'd get them driven from
-   * the done IRQ handler, but I haven't verified that.
+   * These are the wrong events to be watching.  We need to use the
+   * ones under CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS instead.
    */
+#if 0
   { DRM_I915_BEGIN, "i915/i915_gem_request_add",
     (const char *[]){ "ctx", "ring", "seqno", NULL } },
   { DRM_I915_END, "i915/i915_gem_request_retire",
     (const char *[]){ "ctx", "ring", "seqno", NULL } },
+#endif
 };
 
 /* Struct describing tracepoint events.