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Date: Mon, 23 May 2016 15:05:08 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Andi Kleen <andi@...stfloor.org>
Cc: acme@...nel.org, jolsa@...nel.org, linux-kernel@...r.kernel.org,
Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/2] perf pt: Mark PT return events as "return"
On 20/05/16 22:52, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
>
> With perf script --itrace=cr we can synthesize calls and returns out of
> a PT log. However both calls and returns are marked with the same event,
> called branches. This makes it difficult to read and post process,
> because calls and returns are somewhat diffferent.
Did you consider the sample flags?
e.g.
perf script --itrace=cre -F pid,tid,comm,dso,event,ip,sym,symoff,addr,flags
...
uname 1807/1807 branches:u: bB 0 [unknown] ([unknown]) => 7fc78a81e18c brk+0xc (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: br 7fc78a81e1a5 brk+0x25 (/lib/x86_64-linux-gnu/ld-2.19.so) => 7fc78a81d508 _dl_sysdep_start+0x148 (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: bc 7fc78a81d630 _dl_sysdep_start+0x270 (/lib/x86_64-linux-gnu/ld-2.19.so) => 7fc78a81fca0 strlen+0x0 (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: br 7fc78a81fd88 strlen+0xe8 (/lib/x86_64-linux-gnu/ld-2.19.so) => 7fc78a81d635 _dl_sysdep_start+0x275 (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: bc 7fc78a81d52a _dl_sysdep_start+0x16a (/lib/x86_64-linux-gnu/ld-2.19.so) => 7fc78a81e1e0 sbrk+0x0 (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: br 7fc78a81e222 sbrk+0x42 (/lib/x86_64-linux-gnu/ld-2.19.so) => 7fc78a81d52f _dl_sysdep_start+0x16f (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: bc 7fc78a81d563 _dl_sysdep_start+0x1a3 (/lib/x86_64-linux-gnu/ld-2.19.so) => 7fc78a807910 dl_main+0x0 (/lib/x86_64-linux-gnu/ld-2.19.so)
uname 1807/1807 branches:u: bE 7fc78a807929 dl_main+0x19 (/lib/x86_64-linux-gnu/ld-2.19.so) => 0 [unknown] ([unknown])
...
You can see 'c' and 'r' flags for calls and returns.
>
> Create a separate return event and mark the returns as return.
>
> Cc: adrian.hunter@...el.com
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
> tools/perf/util/intel-pt.c | 53 +++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 48 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index ddec87f6e616..25f839e765ef 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -82,9 +82,12 @@ struct intel_pt {
> u64 instructions_id;
>
> bool sample_branches;
> + bool sample_returns;
> u32 branches_filter;
> u64 branches_sample_type;
> + u64 returns_sample_type;
> u64 branches_id;
> + u64 returns_id;
>
> bool sample_transactions;
> u64 transactions_sample_type;
> @@ -960,7 +963,8 @@ static int intel_pt_inject_event(union perf_event *event,
> return perf_event__synthesize_sample(event, type, 0, sample, swapped);
> }
>
> -static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
> +static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq,
> + bool is_return)
> {
> int ret;
> struct intel_pt *pt = ptq->pt;
> @@ -990,8 +994,13 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
> sample.pid = ptq->pid;
> sample.tid = ptq->tid;
> sample.addr = ptq->state->to_ip;
> - sample.id = ptq->pt->branches_id;
> - sample.stream_id = ptq->pt->branches_id;
> + if (is_return) {
> + sample.id = ptq->pt->returns_id;
> + sample.stream_id = ptq->pt->returns_id;
> + } else {
> + sample.id = ptq->pt->branches_id;
> + sample.stream_id = ptq->pt->branches_id;
> + }
> sample.period = 1;
> sample.cpu = ptq->cpu;
> sample.flags = ptq->flags;
> @@ -1014,6 +1023,8 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq)
>
> if (pt->synth_opts.inject) {
> ret = intel_pt_inject_event(event, &sample,
> + is_return ?
> + pt->returns_sample_type :
> pt->branches_sample_type,
> pt->synth_needs_swap);
> if (ret)
> @@ -1241,7 +1252,13 @@ static int intel_pt_sample(struct intel_pt_queue *ptq)
> thread_stack__set_trace_nr(ptq->thread, state->trace_nr);
>
> if (pt->sample_branches) {
> - err = intel_pt_synth_branch_sample(ptq);
> + err = intel_pt_synth_branch_sample(ptq, false);
> + if (err)
> + return err;
> + }
> +
> + if (pt->sample_returns) {
> + err = intel_pt_synth_branch_sample(ptq, true);
> if (err)
> return err;
> }
> @@ -1956,7 +1973,33 @@ static int intel_pt_synth_events(struct intel_pt *pt,
> }
> pt->sample_branches = true;
> pt->branches_sample_type = attr.sample_type;
> - pt->branches_id = id;
> + pt->branches_id = id++;
> + }
> + if (pt->synth_opts.returns) {
> + attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
> + attr.sample_period = 1;
> + attr.sample_type |= PERF_SAMPLE_ADDR;
> + attr.sample_type &= ~(u64)PERF_SAMPLE_CALLCHAIN;
> + attr.sample_type &= ~(u64)PERF_SAMPLE_BRANCH_STACK;
> + pr_debug("Synthesizing 'return' event with id %" PRIu64 " sample type %#" PRIx64 "\n",
> + id, (u64)attr.sample_type);
> + err = intel_pt_synth_event(session, &attr, id);
> + if (err) {
> + pr_err("%s: failed to synthesize 'return' event type\n",
> + __func__);
> + return err;
> + }
> + pt->sample_returns = true;
> + pt->returns_sample_type = attr.sample_type;
> + pt->returns_id = id;
> + evlist__for_each(evlist, evsel) {
> + if (evsel->id && evsel->id[0] == pt->returns_id) {
> + if (evsel->name)
> + zfree(&evsel->name);
> + evsel->name = strdup("return");
> + break;
> + }
> + }
> }
>
> pt->synth_needs_swap = evsel->needs_swap;
>
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