linux-kernel - [PATCH 1/7] perf intel-pt: Decoder to output CBR changes immediately

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Message-Id: <20190622093248.581-2-adrian.hunter@intel.com>
Date:   Sat, 22 Jun 2019 12:32:42 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/7] perf intel-pt: Decoder to output CBR changes immediately

The core-to-bus ratio (CBR) provides the CPU frequency. With branches
enabled, the decoder was outputting CBR changes only when there was a
branch. That loses the correct time of the change if the trace is not in
context (e.g. not tracing kernel space). Change to output the CBR change
immediately.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 .../util/intel-pt-decoder/intel-pt-decoder.c     | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 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 f8b71bf2bb4c..3d2255f284f4 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -2015,16 +2015,8 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
 
 		case INTEL_PT_CBR:
 			intel_pt_calc_cbr(decoder);
-			if (!decoder->branch_enable &&
-			    decoder->cbr != decoder->cbr_seen) {
-				decoder->cbr_seen = decoder->cbr;
-				decoder->state.type = INTEL_PT_CBR_CHG;
-				decoder->state.from_ip = decoder->ip;
-				decoder->state.to_ip = 0;
-				decoder->state.cbr_payload =
-							decoder->packet.payload;
+			if (decoder->cbr != decoder->cbr_seen)
 				return 0;
-			}
 			break;
 
 		case INTEL_PT_MODE_EXEC:
@@ -2626,8 +2618,12 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
 		decoder->sample_tot_cyc_cnt = decoder->tot_cyc_cnt;
 	} else {
 		decoder->state.err = 0;
-		if (decoder->cbr != decoder->cbr_seen && decoder->state.type) {
+		if (decoder->cbr != decoder->cbr_seen) {
 			decoder->cbr_seen = decoder->cbr;
+			if (!decoder->state.type) {
+				decoder->state.from_ip = decoder->ip;
+				decoder->state.to_ip = 0;
+			}
 			decoder->state.type |= INTEL_PT_CBR_CHG;
 			decoder->state.cbr_payload = decoder->cbr_payload;
 		}
-- 
2.17.1