From d1706b39f0af6901ab2a5e2ebb210b53c1a5bdc7 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Mon, 28 Mar 2016 10:45:38 -0700 Subject: 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 Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Jiri Olsa Cc: Stephane Eranian Link: http://lkml.kernel.org/r/1459187142-20035-1-git-send-email-andi@firstfloor.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/intel-bts.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'tools/perf/util/intel-bts.c') diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c index abf1366e2a24..9df996085563 100644 --- a/tools/perf/util/intel-bts.c +++ b/tools/perf/util/intel-bts.c @@ -66,6 +66,7 @@ struct intel_bts { u64 branches_id; size_t branches_event_size; bool synth_needs_swap; + unsigned long num_events; }; struct intel_bts_queue { @@ -275,6 +276,10 @@ static int intel_bts_synth_branch_sample(struct intel_bts_queue *btsq, 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); -- cgit v1.2.3