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Patch "perf intel-pt: Improve sample timestamp" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jul 22, 2017

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This is a note to let you know that I've just added the patch titled

perf intel-pt: Improve sample timestamp

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
perf-intel-pt-improve-sample-timestamp.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 3f04d98e972b59706bd43d6cc75efac91f8fba50 Mon Sep 17 00:00:00 2001

From: Adrian Hunter <[email protected]>
Date: Fri, 26 May 2017 11:17:03 +0300
Subject: perf intel-pt: Improve sample timestamp

From: Adrian Hunter <[email protected]>

commit 3f04d98e972b59706bd43d6cc75efac91f8fba50 upstream.

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 <[email protected]>
Cc Andi Kleen <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c |   34 ++++++++++++++++++--
 1 file changed, 31 insertions(+), 3 deletions(-)
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c +31 -3
@@ -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

@@ -99,6 +118,7 @@ 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;

@@ -139,6 +159,7 @@ struct intel_pt_decoder {
 	unsigned int fup_tx_flags;
 	unsigned int tx_flags;
 	uint64_t timestamp_insn_cnt;
+	uint64_t sample_insn_cnt;
 	uint64_t stuck_ip;
 	int no_progress;
 	int stuck_ip_prd;

@@ -898,6 +919,7 @@ static int intel_pt_walk_insn(struct int
 
 	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) {

@@ -2067,7 +2089,7 @@ static int intel_pt_sync(struct intel_pt
 
 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;

@@ -2075,7 +2097,7 @@ static uint64_t intel_pt_est_timestamp(s
 	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)

@@ -2131,11 +2153,17 @@ const struct intel_pt_state *intel_pt_de
 	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 (intel_pt_sample_time(decoder->pkt_state)) {
+			decoder->sample_timestamp = decoder->timestamp;
+			decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
+		}
 	}
 
-	decoder->state.timestamp = decoder->timestamp;
+	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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/perf-intel-pt-ensure-ip-is-zero-when-state-is-intel_pt_state_no_ip.patch queue-4.9/perf-intel-pt-ensure-never-to-set-last_ip-when-packet-count-is-zero.patch queue-4.9/perf-intel-pt-use-fup-always-when-scanning-for-an-ip.patch queue-4.9/perf-intel-pt-fix-last_ip-usage.patch queue-4.9/perf-intel-pt-move-decoder-error-setting-into-one-condition.patch queue-4.9/perf-intel-pt-clear-fup-flag-on-error.patch queue-4.9/perf-intel-pt-improve-sample-timestamp.patch queue-4.9/perf-intel-pt-fix-missing-stack-clear.patch