perf/core: Add weighted samples

For some events it's useful to weight sample with a hardware
provided number. This expresses how expensive the action the
sample represent was.  This allows the profiler to scale
the samples to be more informative to the programmer.

There is already the period which is used similarly, but it
means something different, so I chose to not overload it.
Instead a new sample type for WEIGHT is added.

Can be used for multiple things. Initially it is used for TSX
abort costs and profiling by memory latencies (so to make
expensive load appear higher up in the histograms). The concept
is quite generic and can be extended to many other kinds of
events or architectures, as long as the hardware provides
suitable auxillary values. In principle it could be also used
for software tracepoints.

This adds the generic glue. A new optional sample format for a
64-bit weight value.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: acme@redhat.com
Cc: jolsa@redhat.com
Cc: namhyung.kim@lge.com
Link: http://lkml.kernel.org/r/1359040242-8269-5-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 9fa9c622a7f4..cdc255da02e2 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -132,8 +132,10 @@ enum perf_event_sample_format {
         PERF_SAMPLE_BRANCH_STACK                = 1U << 11,
         PERF_SAMPLE_REGS_USER                   = 1U << 12,
         PERF_SAMPLE_STACK_USER                  = 1U << 13,
+        PERF_SAMPLE_WEIGHT                      = 1U << 14,
+
+        PERF_SAMPLE_MAX = 1U << 15,             /* non-ABI */
 
-        PERF_SAMPLE_MAX = 1U << 14,             /* non-ABI */
 };
 
 /*
@@ -588,6 +590,8 @@ enum perf_event_type {
          *      { u64                   size;
          *        char                  data[size];
          *        u64                   dyn_size; } && PERF_SAMPLE_STACK_USER
+         *
+         *      { u64                   weight;   } && PERF_SAMPLE_WEIGHT
          * };
          */
         PERF_RECORD_SAMPLE                      = 9,