perf intel-pt: Support generating branch stack
authorAdrian Hunter <adrian.hunter@intel.com>
Fri, 25 Sep 2015 13:15:45 +0000 (16:15 +0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Mon, 28 Sep 2015 19:59:14 +0000 (16:59 -0300)
commitf14445ee72c59f32aa5cbf4d0f0330a5f62a752d
tree6498ddc2acfef1a06f1b5cf10606b8f1171dbc9e
parent385e33063fb963f5cccb0a37fe539319b6481fa5
perf intel-pt: Support generating branch stack

Add support for generating branch stack context for PT samples.  The
decoder reports a configurable number of branches as branch context for
each sample. Internally it keeps track of them by using a simple sliding
window.  We also flush the last branch buffer on each sample to avoid
overlapping intervals.

This is useful for:

- Reporting accurate basic block edge frequencies through the perf
  report branch view
- Using with --branch-history to get the wider context of samples
- Other users of LBRs

Also the Documentation is updated.

Examples:

Record with Intel PT:

perf record -e intel_pt//u ls

Branch stacks are used by default if synthesized so:

perf report --itrace=ile

is the same as:

perf report --itrace=ile -b

Branch history can be requested also:

perf report --itrace=igle --branch-history

Based-on-patch-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1443186956-18718-15-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/Documentation/intel-pt.txt
tools/perf/util/intel-pt.c