perf tools: Add support for skipping itrace instructions
When using 'perf script' to look at PT traces it is often useful to
ignore the initialization code at the beginning.
On larger traces which may have many millions of instructions in
initialization code doing that in a pipeline can be very slow, with perf
script spending a lot of CPU time calling printf and writing data.
This patch adds an extension to the --itrace argument that skips 'n'
events (instructions, branches or transactions) at the beginning. This
is much more efficient.
v2:
Add support for BTS (Adrian Hunter)
Document in itrace.txt
Fix branch check
Check transactions and instructions too
Committer note:
To test intel_pt one needs to make sure VT-x isn't active, i.e.
stopping KVM guests on the test machine, as described by Andi Kleen
at http://lkml.kernel.org/r/20160301234953.GD23621@tassilo.jf.intel.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1459187142-20035-1-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index abf1366..9df9960 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -66,6 +66,7 @@
u64 branches_id;
size_t branches_event_size;
bool synth_needs_swap;
+ unsigned long num_events;
};
struct intel_bts_queue {
@@ -275,6 +276,10 @@
union perf_event event;
struct perf_sample sample = { .ip = 0, };
+ if (bts->synth_opts.initial_skip &&
+ bts->num_events++ <= bts->synth_opts.initial_skip)
+ return 0;
+
event.sample.header.type = PERF_RECORD_SAMPLE;
event.sample.header.misc = PERF_RECORD_MISC_USER;
event.sample.header.size = sizeof(struct perf_event_header);