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| author | Adrian Hunter <adrian.hunter@intel.com> | 2015-09-25 16:15:45 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2015-09-28 22:59:14 +0300 |
| commit | f14445ee72c59f32aa5cbf4d0f0330a5f62a752d (patch) | |
| tree | 6498ddc2acfef1a06f1b5cf10606b8f1171dbc9e /tools/perf/Documentation | |
| parent | 385e33063fb963f5cccb0a37fe539319b6481fa5 (diff) | |
| download | linux-f14445ee72c59f32aa5cbf4d0f0330a5f62a752d.tar.xz | |
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>
Diffstat (limited to 'tools/perf/Documentation')
| -rw-r--r-- | tools/perf/Documentation/intel-pt.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/tools/perf/Documentation/intel-pt.txt b/tools/perf/Documentation/intel-pt.txt index 886612b50961..a0fbb5d71f7d 100644 --- a/tools/perf/Documentation/intel-pt.txt +++ b/tools/perf/Documentation/intel-pt.txt @@ -671,6 +671,7 @@ The letters are: e synthesize tracing error events d create a debug log g synthesize a call chain (use with i or x) + l synthesize last branch entries (use with i or x) "Instructions" events look like they were recorded by "perf record -e instructions". @@ -718,6 +719,15 @@ transactions events can be specified. e.g. --itrace=ig32 --itrace=xg32 +Also the number of last branch entries (default 64, max. 1024) for instructions or +transactions events can be specified. e.g. + + --itrace=il10 + --itrace=xl10 + +Note that last branch entries are cleared for each sample, so there is no overlap +from one sample to the next. + To disable trace decoding entirely, use the option --no-itrace. |