From: Adrian Hunter <adrian.hunter@intel.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>, Andi Kleen <ak@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH V2 10/12] perf intel-pt: Better 7-byte timestamp wraparound logic
Date: Fri, 30 Apr 2021 10:03:07 +0300 [thread overview]
Message-ID: <20210430070309.17624-11-adrian.hunter@intel.com> (raw)
In-Reply-To: <20210430070309.17624-1-adrian.hunter@intel.com>
A timestamp should not go backwards. If it does it is assumed that the
7-byte TSC packet value has wrapped. Improve that logic so that it will
not allow the timestamp to go past the buffer timestamp (which is recorded
when the buffer is copied out)
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 12 +++++++++---
1 file changed, 9 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 7c93ae2bd56c..c4044bc2fb86 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1499,9 +1499,15 @@ static void intel_pt_calc_tsc_timestamp(struct intel_pt_decoder *decoder)
timestamp = decoder->timestamp;
}
if (timestamp < decoder->timestamp) {
- intel_pt_log_to("Wraparound timestamp", timestamp);
- timestamp += (1ULL << 56);
- decoder->tsc_timestamp = timestamp;
+ if (!decoder->buf_timestamp ||
+ (timestamp + (1ULL << 56) < decoder->buf_timestamp)) {
+ intel_pt_log_to("Wraparound timestamp", timestamp);
+ timestamp += (1ULL << 56);
+ decoder->tsc_timestamp = timestamp;
+ } else {
+ intel_pt_log_to("Suppressing bad timestamp", timestamp);
+ timestamp = decoder->timestamp;
+ }
}
decoder->timestamp = timestamp;
decoder->timestamp_insn_cnt = 0;
--
2.25.1
next prev parent reply other threads:[~2021-04-30 7:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 7:02 [PATCH V2 00/12] perf intel-pt: Add more support for VMs Adrian Hunter
2021-04-30 7:02 ` [PATCH V2 01/12] perf auxtrace: Add Z itrace option for timeless decoding Adrian Hunter
2021-04-30 7:02 ` [PATCH V2 02/12] perf intel-pt: Move synth_opts initialization earlier Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 03/12] perf intel-pt: Support Z itrace option for timeless decoding Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 04/12] perf inject: Add facility to do in place update Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 05/12] perf inject: Add --vm-time-correlation option Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 06/12] perf auxtrace: Allow buffers to be mapped read / write Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 07/12] perf intel-pt: Let overlap detection handle VM timestamps Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 08/12] perf intel-pt: Add a tree for VMCS information Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 09/12] perf intel-pt: Pass the first timestamp to the decoder Adrian Hunter
2021-04-30 7:03 ` Adrian Hunter [this message]
2021-04-30 7:03 ` [PATCH V2 11/12] perf intel-pt: Add VM Time Correlation to decoder Adrian Hunter
2021-04-30 7:03 ` [PATCH V2 12/12] perf intel-pt: Parse VM Time Correlation options and set up decoding Adrian Hunter
2021-04-30 21:29 ` [PATCH V2 00/12] perf intel-pt: Add more support for VMs Andi Kleen
2021-05-03 15:09 ` Arnaldo Carvalho de Melo
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