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Subject[PATCH 37/37] perf intel-pt: Improve sample timestamp
Date
The decoder uses its current timestamp in samples. Usually that is a
timestamp that has already passed, but in some cases it is a timestamp for
a branch that the decoder is walking towards, and consequently hasn't
reached. Improve that situation by using the pkt_state to determine when
to use the current or previous timestamp.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
.../perf/util/intel-pt-decoder/intel-pt-decoder.c | 42 ++++++++++++++++++----
1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
index a6f41a0e1ae8..aa1593ce551d 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -64,6 +64,25 @@ enum intel_pt_pkt_state {
INTEL_PT_STATE_FUP_NO_TIP,
};

+static inline bool intel_pt_sample_time(enum intel_pt_pkt_state pkt_state)
+{
+ switch (pkt_state) {
+ case INTEL_PT_STATE_NO_PSB:
+ case INTEL_PT_STATE_NO_IP:
+ case INTEL_PT_STATE_ERR_RESYNC:
+ case INTEL_PT_STATE_IN_SYNC:
+ case INTEL_PT_STATE_TNT:
+ return true;
+ case INTEL_PT_STATE_TIP:
+ case INTEL_PT_STATE_TIP_PGD:
+ case INTEL_PT_STATE_FUP:
+ case INTEL_PT_STATE_FUP_NO_TIP:
+ return false;
+ default:
+ return true;
+ };
+}
+
#ifdef INTEL_PT_STRICT
#define INTEL_PT_STATE_ERR1 INTEL_PT_STATE_NO_PSB
#define INTEL_PT_STATE_ERR2 INTEL_PT_STATE_NO_PSB
@@ -101,6 +120,7 @@ struct intel_pt_decoder {
uint64_t timestamp;
uint64_t tsc_timestamp;
uint64_t ref_timestamp;
+ uint64_t sample_timestamp;
uint64_t ret_addr;
uint64_t ctc_timestamp;
uint64_t ctc_delta;
@@ -150,6 +170,7 @@ struct intel_pt_decoder {
uint64_t fup_pwre_payload;
uint64_t cbr_payload;
uint64_t timestamp_insn_cnt;
+ uint64_t sample_insn_cnt;
uint64_t stuck_ip;
int no_progress;
int stuck_ip_prd;
@@ -932,6 +953,7 @@ static int intel_pt_walk_insn(struct intel_pt_decoder *decoder,

decoder->tot_insn_cnt += insn_cnt;
decoder->timestamp_insn_cnt += insn_cnt;
+ decoder->sample_insn_cnt += insn_cnt;
decoder->period_insn_cnt += insn_cnt;

if (err) {
@@ -2279,7 +2301,7 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)

static uint64_t intel_pt_est_timestamp(struct intel_pt_decoder *decoder)
{
- uint64_t est = decoder->timestamp_insn_cnt << 1;
+ uint64_t est = decoder->sample_insn_cnt << 1;

if (!decoder->cbr || !decoder->max_non_turbo_ratio)
goto out;
@@ -2287,7 +2309,7 @@ static uint64_t intel_pt_est_timestamp(struct intel_pt_decoder *decoder)
est *= decoder->max_non_turbo_ratio;
est /= decoder->cbr;
out:
- return decoder->timestamp + est;
+ return decoder->sample_timestamp + est;
}

const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
@@ -2342,14 +2364,11 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
}
} while (err == -ENOLINK);

- decoder->state.timestamp = decoder->timestamp;
- decoder->state.est_timestamp = intel_pt_est_timestamp(decoder);
- decoder->state.cr3 = decoder->cr3;
- decoder->state.tot_insn_cnt = decoder->tot_insn_cnt;
-
if (err) {
decoder->state.err = intel_pt_ext_err(err);
decoder->state.from_ip = decoder->ip;
+ decoder->sample_timestamp = decoder->timestamp;
+ decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
} else {
decoder->state.err = 0;
if (decoder->cbr != decoder->cbr_seen && decoder->state.type) {
@@ -2357,8 +2376,17 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
decoder->state.type |= INTEL_PT_CBR_CHG;
decoder->state.cbr_payload = decoder->cbr_payload;
}
+ if (intel_pt_sample_time(decoder->pkt_state)) {
+ decoder->sample_timestamp = decoder->timestamp;
+ decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
+ }
}

+ decoder->state.timestamp = decoder->sample_timestamp;
+ decoder->state.est_timestamp = intel_pt_est_timestamp(decoder);
+ decoder->state.cr3 = decoder->cr3;
+ decoder->state.tot_insn_cnt = decoder->tot_insn_cnt;
+
return &decoder->state;
}

--
1.9.1
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