From f14445ee72c59f32aa5cbf4d0f0330a5f62a752d Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Fri, 25 Sep 2015 16:15:45 +0300 Subject: [PATCH] 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 Signed-off-by: Adrian Hunter Cc: Jiri Olsa Link: http://lkml.kernel.org/r/1443186956-18718-15-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/intel-pt.txt | 10 +++ tools/perf/util/intel-pt.c | 115 ++++++++++++++++++++++++++ 2 files changed, 125 insertions(+) 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. diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c index 2c01e723826a..05e8fcc5188b 100644 --- a/tools/perf/util/intel-pt.c +++ b/tools/perf/util/intel-pt.c @@ -22,6 +22,7 @@ #include "../perf.h" #include "session.h" #include "machine.h" +#include "sort.h" #include "tool.h" #include "event.h" #include "evlist.h" @@ -115,6 +116,9 @@ struct intel_pt_queue { void *decoder; const struct intel_pt_state *state; struct ip_callchain *chain; + struct branch_stack *last_branch; + struct branch_stack *last_branch_rb; + size_t last_branch_pos; union perf_event *event_buf; bool on_heap; bool stop; @@ -675,6 +679,19 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt, goto out_free; } + if (pt->synth_opts.last_branch) { + size_t sz = sizeof(struct branch_stack); + + sz += pt->synth_opts.last_branch_sz * + sizeof(struct branch_entry); + ptq->last_branch = zalloc(sz); + if (!ptq->last_branch) + goto out_free; + ptq->last_branch_rb = zalloc(sz); + if (!ptq->last_branch_rb) + goto out_free; + } + ptq->event_buf = malloc(PERF_SAMPLE_MAX_SIZE); if (!ptq->event_buf) goto out_free; @@ -732,6 +749,8 @@ static struct intel_pt_queue *intel_pt_alloc_queue(struct intel_pt *pt, out_free: zfree(&ptq->event_buf); + zfree(&ptq->last_branch); + zfree(&ptq->last_branch_rb); zfree(&ptq->chain); free(ptq); return NULL; @@ -746,6 +765,8 @@ static void intel_pt_free_queue(void *priv) thread__zput(ptq->thread); intel_pt_decoder_free(ptq->decoder); zfree(&ptq->event_buf); + zfree(&ptq->last_branch); + zfree(&ptq->last_branch_rb); zfree(&ptq->chain); free(ptq); } @@ -876,6 +897,57 @@ static int intel_pt_setup_queues(struct intel_pt *pt) return 0; } +static inline void intel_pt_copy_last_branch_rb(struct intel_pt_queue *ptq) +{ + struct branch_stack *bs_src = ptq->last_branch_rb; + struct branch_stack *bs_dst = ptq->last_branch; + size_t nr = 0; + + bs_dst->nr = bs_src->nr; + + if (!bs_src->nr) + return; + + nr = ptq->pt->synth_opts.last_branch_sz - ptq->last_branch_pos; + memcpy(&bs_dst->entries[0], + &bs_src->entries[ptq->last_branch_pos], + sizeof(struct branch_entry) * nr); + + if (bs_src->nr >= ptq->pt->synth_opts.last_branch_sz) { + memcpy(&bs_dst->entries[nr], + &bs_src->entries[0], + sizeof(struct branch_entry) * ptq->last_branch_pos); + } +} + +static inline void intel_pt_reset_last_branch_rb(struct intel_pt_queue *ptq) +{ + ptq->last_branch_pos = 0; + ptq->last_branch_rb->nr = 0; +} + +static void intel_pt_update_last_branch_rb(struct intel_pt_queue *ptq) +{ + const struct intel_pt_state *state = ptq->state; + struct branch_stack *bs = ptq->last_branch_rb; + struct branch_entry *be; + + if (!ptq->last_branch_pos) + ptq->last_branch_pos = ptq->pt->synth_opts.last_branch_sz; + + ptq->last_branch_pos -= 1; + + be = &bs->entries[ptq->last_branch_pos]; + be->from = state->from_ip; + be->to = state->to_ip; + be->flags.abort = !!(state->flags & INTEL_PT_ABORT_TX); + be->flags.in_tx = !!(state->flags & INTEL_PT_IN_TX); + /* No support for mispredict */ + + if (bs->nr < ptq->pt->synth_opts.last_branch_sz) + bs->nr += 1; +} + static int intel_pt_inject_event(union perf_event *event, struct perf_sample *sample, u64 type, bool swapped) @@ -890,6 +962,10 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq) struct intel_pt *pt = ptq->pt; union perf_event *event = ptq->event_buf; struct perf_sample sample = { .ip = 0, }; + struct dummy_branch_stack { + u64 nr; + struct branch_entry entries; + } dummy_bs; if (pt->branches_filter && !(pt->branches_filter & ptq->flags)) return 0; @@ -912,6 +988,21 @@ static int intel_pt_synth_branch_sample(struct intel_pt_queue *ptq) sample.flags = ptq->flags; sample.insn_len = ptq->insn_len; + /* + * perf report cannot handle events without a branch stack when using + * SORT_MODE__BRANCH so make a dummy one. + */ + if (pt->synth_opts.last_branch && sort__mode == SORT_MODE__BRANCH) { + dummy_bs = (struct dummy_branch_stack){ + .nr = 1, + .entries = { + .from = sample.ip, + .to = sample.addr, + }, + }; + sample.branch_stack = (struct branch_stack *)&dummy_bs; + } + if (pt->synth_opts.inject) { ret = intel_pt_inject_event(event, &sample, pt->branches_sample_type, @@ -961,6 +1052,11 @@ static int intel_pt_synth_instruction_sample(struct intel_pt_queue *ptq) sample.callchain = ptq->chain; } + if (pt->synth_opts.last_branch) { + intel_pt_copy_last_branch_rb(ptq); + sample.branch_stack = ptq->last_branch; + } + if (pt->synth_opts.inject) { ret = intel_pt_inject_event(event, &sample, pt->instructions_sample_type, @@ -974,6 +1070,9 @@ static int intel_pt_synth_instruction_sample(struct intel_pt_queue *ptq) pr_err("Intel Processor Trace: failed to deliver instruction event, error %d\n", ret); + if (pt->synth_opts.last_branch) + intel_pt_reset_last_branch_rb(ptq); + return ret; } @@ -1008,6 +1107,11 @@ static int intel_pt_synth_transaction_sample(struct intel_pt_queue *ptq) sample.callchain = ptq->chain; } + if (pt->synth_opts.last_branch) { + intel_pt_copy_last_branch_rb(ptq); + sample.branch_stack = ptq->last_branch; + } + if (pt->synth_opts.inject) { ret = intel_pt_inject_event(event, &sample, pt->transactions_sample_type, @@ -1021,6 +1125,9 @@ static int intel_pt_synth_transaction_sample(struct intel_pt_queue *ptq) pr_err("Intel Processor Trace: failed to deliver transaction event, error %d\n", ret); + if (pt->synth_opts.callchain) + intel_pt_reset_last_branch_rb(ptq); + return ret; } @@ -1116,6 +1223,9 @@ static int intel_pt_sample(struct intel_pt_queue *ptq) return err; } + if (pt->synth_opts.last_branch) + intel_pt_update_last_branch_rb(ptq); + if (!pt->sync_switch) return 0; @@ -1763,6 +1873,8 @@ static int intel_pt_synth_events(struct intel_pt *pt, pt->instructions_sample_period = attr.sample_period; if (pt->synth_opts.callchain) attr.sample_type |= PERF_SAMPLE_CALLCHAIN; + if (pt->synth_opts.last_branch) + attr.sample_type |= PERF_SAMPLE_BRANCH_STACK; pr_debug("Synthesizing 'instructions' event with id %" PRIu64 " sample type %#" PRIx64 "\n", id, (u64)attr.sample_type); err = intel_pt_synth_event(session, &attr, id); @@ -1782,6 +1894,8 @@ static int intel_pt_synth_events(struct intel_pt *pt, attr.sample_period = 1; if (pt->synth_opts.callchain) attr.sample_type |= PERF_SAMPLE_CALLCHAIN; + if (pt->synth_opts.last_branch) + attr.sample_type |= PERF_SAMPLE_BRANCH_STACK; pr_debug("Synthesizing 'transactions' event with id %" PRIu64 " sample type %#" PRIx64 "\n", id, (u64)attr.sample_type); err = intel_pt_synth_event(session, &attr, id); @@ -1808,6 +1922,7 @@ static int intel_pt_synth_events(struct intel_pt *pt, 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 'branches' event with id %" PRIu64 " sample type %#" PRIx64 "\n", id, (u64)attr.sample_type); err = intel_pt_synth_event(session, &attr, id); -- 2.20.1