[PATCH 67/73] perf intel-pt: Fix instructions sampling rate

[PATCH 67/73] perf intel-pt: Fix instructions sampling rate

[Arnaldo Carvalho de Melo]

From: Adrian Hunter <adrian.hunter@intel.com>

The timestamp used to determine if an instruction sample is made, is an
estimate based on the number of instructions since the last known
timestamp. A consequence is that it might go backwards, which results in
extra samples. Change it so that a sample is only made when the
timestamp goes forwards.

Note this does not affect a sampling period of 0 or sampling periods
specified as a count of instructions.

Example:

 Before:

 $ perf script --itrace=i10us
 ls 13812 [003] 2167315.222583:       3270 instructions:u:      7fac71e2e494 __GI___tunables_init+0xf4 (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:      30902 instructions:u:      7fac71e2da0f _dl_cache_libcmp+0x2f (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:         10 instructions:u:      7fac71e2d9ff _dl_cache_libcmp+0x1f (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:          8 instructions:u:      7fac71e2d9ea _dl_cache_libcmp+0xa (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:         14 instructions:u:      7fac71e2d9ea _dl_cache_libcmp+0xa (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:          6 instructions:u:      7fac71e2d9ff _dl_cache_libcmp+0x1f (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:         14 instructions:u:      7fac71e2d9ff _dl_cache_libcmp+0x1f (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:          4 instructions:u:      7fac71e2dab2 _dl_cache_libcmp+0xd2 (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222728:      16423 instructions:u:      7fac71e2477a _dl_map_object_deps+0x1ba (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222734:      12731 instructions:u:      7fac71e27938 _dl_name_match_p+0x68 (/lib/x86_64-linux-gnu/ld-2.28.so)
 ...

 After:
 $ perf script --itrace=i10us
 ls 13812 [003] 2167315.222583:       3270 instructions:u:      7fac71e2e494 __GI___tunables_init+0xf4 (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222667:      30902 instructions:u:      7fac71e2da0f _dl_cache_libcmp+0x2f (/lib/x86_64-linux-gnu/ld-2.28.so)
 ls 13812 [003] 2167315.222728:      16479 instructions:u:      7fac71e2477a _dl_map_object_deps+0x1ba (/lib/x86_64-linux-gnu/ld-2.28.so)
 ...

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Fixes: f4aa081949e7b ("perf tools: Add Intel PT decoder")
Link: http://lkml.kernel.org/r/20190510124143.27054-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 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 872fab163585..26dbf11e071a 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -888,16 +888,20 @@ static uint64_t intel_pt_next_period(struct intel_pt_decoder *decoder)
 	timestamp = decoder->timestamp + decoder->timestamp_insn_cnt;
 	masked_timestamp = timestamp & decoder->period_mask;
 	if (decoder->continuous_period) {
-		if (masked_timestamp != decoder->last_masked_timestamp)
+		if (masked_timestamp > decoder->last_masked_timestamp)
 			return 1;
 	} else {
 		timestamp += 1;
 		masked_timestamp = timestamp & decoder->period_mask;
-		if (masked_timestamp != decoder->last_masked_timestamp) {
+		if (masked_timestamp > decoder->last_masked_timestamp) {
 			decoder->last_masked_timestamp = masked_timestamp;
 			decoder->continuous_period = true;
 		}
 	}
+
+	if (masked_timestamp < decoder->last_masked_timestamp)
+		return decoder->period_ticks;
+
 	return decoder->period_ticks - (timestamp - masked_timestamp);
 }
 
@@ -926,7 +930,10 @@ static void intel_pt_sample_insn(struct intel_pt_decoder *decoder)
 	case INTEL_PT_PERIOD_TICKS:
 		timestamp = decoder->timestamp + decoder->timestamp_insn_cnt;
 		masked_timestamp = timestamp & decoder->period_mask;
-		decoder->last_masked_timestamp = masked_timestamp;
+		if (masked_timestamp > decoder->last_masked_timestamp)
+			decoder->last_masked_timestamp = masked_timestamp;
+		else
+			decoder->last_masked_timestamp += decoder->period_ticks;
 		break;
 	case INTEL_PT_PERIOD_NONE:
 	case INTEL_PT_PERIOD_MTC:
-- 
2.20.1

[PATCH 68/73] perf intel-pt: Fix improved sample timestamp

[Arnaldo Carvalho de Melo]

From: Adrian Hunter <adrian.hunter@intel.com>

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.

The intel_pt_sample_time() function decides which is which, but was not
handling TNT packets exactly correctly.

In the case of TNT, the timestamp applies to the first branch, so the
decoder must first walk to that branch.

That means intel_pt_sample_time() should return true for TNT, and this
patch makes that change. However, if the first branch is a non-taken
branch (i.e. a 'N'), then intel_pt_sample_time() needs to return false
for subsequent taken branches in the same TNT packet.

To handle that, introduce a new state INTEL_PT_STATE_TNT_CONT to
distinguish the cases.

Note that commit 3f04d98e972b5 ("perf intel-pt: Improve sample
timestamp") was also a stable fix and appears, for example, in v4.4
stable tree as commit a4ebb58fd124 ("perf intel-pt: Improve sample
timestamp").

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v4.4+
Fixes: 3f04d98e972b5 ("perf intel-pt: Improve sample timestamp")
Link: http://lkml.kernel.org/r/20190510124143.27054-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 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 26dbf11e071a..9cbd587489bf 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -58,6 +58,7 @@ enum intel_pt_pkt_state {
 	INTEL_PT_STATE_NO_IP,
 	INTEL_PT_STATE_ERR_RESYNC,
 	INTEL_PT_STATE_IN_SYNC,
+	INTEL_PT_STATE_TNT_CONT,
 	INTEL_PT_STATE_TNT,
 	INTEL_PT_STATE_TIP,
 	INTEL_PT_STATE_TIP_PGD,
@@ -72,8 +73,9 @@ static inline bool intel_pt_sample_time(enum intel_pt_pkt_state pkt_state)
 	case INTEL_PT_STATE_NO_IP:
 	case INTEL_PT_STATE_ERR_RESYNC:
 	case INTEL_PT_STATE_IN_SYNC:
-	case INTEL_PT_STATE_TNT:
+	case INTEL_PT_STATE_TNT_CONT:
 		return true;
+	case INTEL_PT_STATE_TNT:
 	case INTEL_PT_STATE_TIP:
 	case INTEL_PT_STATE_TIP_PGD:
 	case INTEL_PT_STATE_FUP:
@@ -1261,7 +1263,9 @@ static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
 				return -ENOENT;
 			}
 			decoder->tnt.count -= 1;
-			if (!decoder->tnt.count)
+			if (decoder->tnt.count)
+				decoder->pkt_state = INTEL_PT_STATE_TNT_CONT;
+			else
 				decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
 			decoder->tnt.payload <<= 1;
 			decoder->state.from_ip = decoder->ip;
@@ -1292,7 +1296,9 @@ static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
 
 		if (intel_pt_insn.branch == INTEL_PT_BR_CONDITIONAL) {
 			decoder->tnt.count -= 1;
-			if (!decoder->tnt.count)
+			if (decoder->tnt.count)
+				decoder->pkt_state = INTEL_PT_STATE_TNT_CONT;
+			else
 				decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
 			if (decoder->tnt.payload & BIT63) {
 				decoder->tnt.payload <<= 1;
@@ -2372,6 +2378,7 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
 			err = intel_pt_walk_trace(decoder);
 			break;
 		case INTEL_PT_STATE_TNT:
+		case INTEL_PT_STATE_TNT_CONT:
 			err = intel_pt_walk_tnt(decoder);
 			if (err == -EAGAIN)
 				err = intel_pt_walk_trace(decoder);
-- 
2.20.1

[PATCH 69/73] perf intel-pt: Fix sample timestamp wrt non-taken branches

[Arnaldo Carvalho de Melo]

From: Adrian Hunter <adrian.hunter@intel.com>

The sample timestamp is updated to ensure that the timestamp represents
the time of the sample and not a branch that the decoder is still
walking towards. The sample timestamp is updated when the decoder
returns, but the decoder does not return for non-taken branches. Update
the sample timestamp then also.

Note that commit 3f04d98e972b5 ("perf intel-pt: Improve sample
timestamp") was also a stable fix and appears, for example, in v4.4
stable tree as commit a4ebb58fd124 ("perf intel-pt: Improve sample
timestamp").

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v4.4+
Fixes: 3f04d98e972b ("perf intel-pt: Improve sample timestamp")
Link: http://lkml.kernel.org/r/20190510124143.27054-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

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 9cbd587489bf..f4c3c84b090f 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1318,8 +1318,11 @@ static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
 				return 0;
 			}
 			decoder->ip += intel_pt_insn.length;
-			if (!decoder->tnt.count)
+			if (!decoder->tnt.count) {
+				decoder->sample_timestamp = decoder->timestamp;
+				decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
 				return -EAGAIN;
+			}
 			decoder->tnt.payload <<= 1;
 			continue;
 		}
-- 
2.20.1