Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1679179
| From | Arnaldo Carvalho de Melo <acme@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 29/30] perf intel-pt: Do not use TSC packets for calculating CPU cycles to TSC |
| Date | 2017-07-01 00:30 +0200 |
| Message-ID | <tYcAj-2OP-41@gated-at.bofh.it> (permalink) |
| References | <tYcAh-2OP-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Adrian Hunter <adrian.hunter@intel.com> 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> Cc: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/1495786658-18063-37-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 5dea06289db5..aa1593ce551d 100644 --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c @@ -711,6 +711,12 @@ 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 && @@ -828,6 +834,14 @@ 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); } -- 2.9.4
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[GIT PULL 00/30] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 03/30] perf help: Elliminate dup code for reporting Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 12/30] x86/insn: perf tools: Add new ptwrite instruction Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 19/30] perf intel-pt: Factor out common code synthesizing event samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 30/30] perf auxtrace: Add CPU filter support Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 08/30] perf tools: Replace error() with pr_err() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 05/30] perf config: Use pr_warning() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 22/30] perf intel-pt: Tidy Intel PT evsel lookup into separate function Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 25/30] perf intel-pt: Move code in intel_pt_synth_events() to simplify attr setting Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 11/30] perf jit: fix typo: "incalid" -> "invalid" Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 24/30] perf intel-pt: Factor out intel_pt_set_event_name() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 20/30] perf intel-pt: Remove unused instructions_sample_period Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 14/30] tools include: Add byte-swapping macros to kernel.h Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 04/30] perf help: Use pr_warning() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 27/30] perf intel-pt: Add example script for power events and PTWRITE Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 29/30] perf intel-pt: Do not use TSC packets for calculating CPU cycles to TSC Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 17/30] perf script: Add 'synth' field for synthesized event payloads Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 26/30] perf intel-pt: Synthesize new power and "ptwrite" events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 15/30] perf auxtrace: Add itrace option to output ptwrite events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 01/30] perf tests: Add platform dependency to test 15 Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 23/30] perf intel-pt: Tidy messages into called function intel_pt_synth_event() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 28/30] perf intel-pt: Update documentation to include new ptwrite and power events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 21/30] perf intel-pt: Join needlessly wrapped lines Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 18/30] perf script: Add synthesized Intel PT power and ptwrite events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:30 +0200 [PATCH 13/30] perf script: Add 'synth' event type for synthesized events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:40 +0200 [PATCH 02/30] perf help: Introduce exec_failed() to avoid code duplication Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:40 +0200 [PATCH 10/30] perf tools: Kill die() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:40 +0200 [PATCH 07/30] perf tools: Remove warning() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:40 +0200 [PATCH 09/30] perf config: Do not die when parsing u64 or int config values Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:40 +0200 [PATCH 16/30] perf auxtrace: Add itrace option to output power events Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-01 00:40 +0200 Re: [GIT PULL 00/30] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2017-07-01 10:50 +0200
csiph-web