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Groups > linux.kernel > #1645426
| From | Adrian Hunter <adrian.hunter@intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 35/37] perf intel-pt: Do not use TSC packets for calculating CPU cycles to TSC |
| Date | 2017-05-19 11:10 +0200 |
| Message-ID | <tIM55-8nS-41@gated-at.bofh.it> (permalink) |
| References | <tIM53-8nS-3@gated-at.bofh.it> |
| Organization | Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki |
CBR (core-to-bus ratio) packets provide an indication of CPU frequency. A more accurate measure can be made by counting the cycles (given by CYC packets) in between other timing packets (either MTC or TSC). Using TSC packets has at least 2 issues: 1) timing might have stopped (e.g. mwait) or 2) TSC packets within PSB+ might slip past CYC packets. For now, simply do not use TSC packets for calculating CPU cycles to TSC. That leaves the case where 2 MTC packets are used, otherwise falling back to the CBR value. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> --- tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) 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 9bb694290a28..a6f41a0e1ae8 100644 --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c @@ -690,6 +690,12 @@ static int intel_pt_calc_cyc_cb(struct intel_pt_pkt_info *pkt_info) break; case INTEL_PT_TSC: + /* + * For now, do not support using TSC packets - refer + * intel_pt_calc_cyc_to_tsc(). + */ + if (data->from_mtc) + return 1; timestamp = pkt_info->packet.payload | (data->timestamp & (0xffULL << 56)); if (data->from_mtc && timestamp < data->timestamp && @@ -807,6 +813,14 @@ static void intel_pt_calc_cyc_to_tsc(struct intel_pt_decoder *decoder, .cbr_cyc_to_tsc = 0, }; + /* + * For now, do not support using TSC packets for at least the reasons: + * 1) timing might have stopped + * 2) TSC packets within PSB+ can slip against CYC packets + */ + if (!from_mtc) + return; + intel_pt_pkt_lookahead(decoder, intel_pt_calc_cyc_cb, &data); } -- 1.9.1
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[PATCH 00/37] perf intel-pt: Power events and PTWRITE Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 30/37] perf intel-pt: Factor out intel_pt_set_event_name() Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 14/37] perf intel-pt: Add decoder support for CBR events Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 27/37] perf intel-pt: Join needlessly wrapped lines Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 17/37] perf tools: Fix message because cpu list option is -C not -c Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 07/37] perf intel-pt: Ensure never to set 'last_ip' when packet 'count' is zero Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 37/37] perf intel-pt: Improve sample timestamp Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
Re: [PATCH 37/37] perf intel-pt: Improve sample timestamp Andi Kleen <ak@linux.intel.com> - 2017-05-19 16:40 +0200
[PATCH 09/37] perf intel-pt: Add missing __fallthrough Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 19/37] perf script: Add 'synth' event type for synthesized events Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 35/37] perf intel-pt: Do not use TSC packets for calculating CPU cycles to TSC Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 05/37] perf intel-pt: Ensure IP is zero when state is INTEL_PT_STATE_NO_IP Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 03/37] perf intel-pt: Add documentation for new config terms Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 26/37] perf intel-pt: Remove unused instructions_sample_period Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 11/37] perf intel-pt: Add decoder support for ptwrite and power event packets Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 18/37] perf script: Fix message because field list option is -F not -f Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 13/37] perf intel-pt: Move decoder error setting into one condition Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 32/37] perf intel-pt: Synthesize new power and ptwrite events Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 15/37] perf intel-pt: Remove redundant initial_skip checks Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 24/37] perf script: Add synthesized Intel PT power and ptwrite events Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 36/37] perf auxtrace: Add CPU filter support Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 23/37] perf auxtrace: Add itrace option to output power events Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 25/37] perf intel-pt: Factor out common code synthesizing event samples Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 04/37] perf intel-pt: Fix missing stack clear Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 20/37] perf script: Add 'synth' field for synthesized event payloads Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 34/37] perf intel-pt: Update documentation to include new ptwrite and power events Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 10/37] perf intel-pt: Clear FUP flag on error Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 28/37] perf intel-pt: Tidy Intel PT evsel lookup into separate function Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 16/37] perf intel-pt: Fix transactions_sample_type Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:10 +0200
[PATCH 01/37] perf intel-pt: Allow decoding with branch tracing disabled Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:20 +0200
[PATCH 02/37] perf intel-pt: Add default config for pass-through branch enable Adrian Hunter <adrian.hunter@intel.com> - 2017-05-19 11:20 +0200
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