Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Date | Thu, 21 Nov 2019 11:28:43 -0300 | Subject | Re: [PATCH 13/15] perf intel-pt: Add support for recording AUX area samples |
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Em Fri, Nov 15, 2019 at 02:42:23PM +0200, Adrian Hunter escreveu: > Set up the default number of mmap pages, default sample size and default > psb_period for AUX area sampling. Add documentation also. > > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > --- > tools/perf/Documentation/intel-pt.txt | 59 ++++++++++++++++++- > tools/perf/arch/x86/util/auxtrace.c | 2 + > tools/perf/arch/x86/util/intel-pt.c | 81 ++++++++++++++++++++++++++- > 3 files changed, 139 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/Documentation/intel-pt.txt b/tools/perf/Documentation/intel-pt.txt > index e0d9e7dd4f17..2cf2d9e9d0da 100644 > --- a/tools/perf/Documentation/intel-pt.txt > +++ b/tools/perf/Documentation/intel-pt.txt > @@ -434,6 +434,56 @@ pwr_evt Enable power events. The power events provide information about > "0" otherwise. > > > +AUX area sampling option > +------------------------ > + > +To select Intel PT "sampling" the AUX area sampling option can be used: > + > + --aux-sample > + > +Optionally it can be followed by the sample size in bytes e.g. > + > + --aux-sample=8192 > + > +In addition, the Intel PT event to sample must be defined e.g. > + > + -e intel_pt//u > + > +Samples on other events will be created containing Intel PT data e.g. the > +following will create Intel PT samples on the branch-misses event, note the > +events must be grouped using {}: > + > + perf record --aux-sample -e '{intel_pt//u,branch-misses:u}' > + > +An alternative to '--aux-sample' is to add the config term 'aux-sample-size' to > +events. In this case, the grouping is implied e.g. > + > + perf record -e intel_pt//u -e branch-misses/aux-sample-size=8192/u > + > +is the same as: > + > + perf record -e '{intel_pt//u,branch-misses/aux-sample-size=8192/u}' > + > +but allows for also using an address filter e.g.: > + > + perf record -e intel_pt//u --filter 'filter * @/bin/ls' -e branch-misses/aux-sample-size=8192/u -- ls
Can we improve this warning?
[root@quaco ~]# perf record -e intel_pt//u --filter 'filter * @/bin/ls' -e branch-misses/aux-sample-size=8192/u -- ls Error: The sys_perf_event_open() syscall returned with 7 (Argument list too long) for event (branch-misses/aux-sample-size=8192/u). /bin/dmesg | grep -i perf may provide additional information.
[root@quaco ~]# [root@quaco ~]# uname -a Linux quaco 5.4.0-rc8 #1 SMP Mon Nov 18 06:15:31 -03 2019 x86_64 x86_64 x86_64 GNU/Linux [root@quaco ~]#
> + > +It is important to select a sample size that is big enough to contain at least > +one PSB packet. If not a warning will be displayed: > + > + Intel PT sample size (%zu) may be too small for PSB period (%zu) > + > +The calculation used for that is: if sample_size <= psb_period + 256 display the > +warning. When sampling is used, psb_period defaults to 0 (2KiB). > + > +The default sample size is 4KiB. > + > +The sample size is passed in aux_sample_size in struct perf_event_attr. The > +sample size is limited by the maximum event size which is 64KiB. It is > +difficult to know how big the event might be without the trace sample attached, > +but the tool validates that the sample size is not greater than 60KiB. > + > + > new snapshot option > ------------------- > > @@ -487,8 +537,8 @@ their mlock limit (which defaults to 64KiB but is not multiplied by the number > of cpus). > > In full-trace mode, powers of two are allowed for buffer size, with a minimum > -size of 2 pages. In snapshot mode, it is the same but the minimum size is > -1 page. > +size of 2 pages. In snapshot mode or sampling mode, it is the same but the > +minimum size is 1 page. > > The mmap size and auxtrace mmap size are displayed if the -vv option is used e.g. > > @@ -501,12 +551,17 @@ Intel PT modes of operation > > Intel PT can be used in 2 modes: > full-trace mode > + sample mode > snapshot mode > > Full-trace mode traces continuously e.g. > > perf record -e intel_pt//u uname > > +Sample mode attaches a Intel PT sample to other events e.g. > + > + perf record --aux-sample -e intel_pt//u -e branch-misses:u > + > Snapshot mode captures the available data when a signal is sent e.g. > > perf record -v -e intel_pt//u -S ./loopy 1000000000 & > diff --git a/tools/perf/arch/x86/util/auxtrace.c b/tools/perf/arch/x86/util/auxtrace.c > index 96f4a2c11893..092543cad324 100644 > --- a/tools/perf/arch/x86/util/auxtrace.c > +++ b/tools/perf/arch/x86/util/auxtrace.c > @@ -26,6 +26,8 @@ struct auxtrace_record *auxtrace_record__init_intel(struct evlist *evlist, > bool found_bts = false; > > intel_pt_pmu = perf_pmu__find(INTEL_PT_PMU_NAME); > + if (intel_pt_pmu) > + intel_pt_pmu->auxtrace = true; > intel_bts_pmu = perf_pmu__find(INTEL_BTS_PMU_NAME); > > evlist__for_each_entry(evlist, evsel) { > diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c > index d6d26256915f..20df442fdf36 100644 > --- a/tools/perf/arch/x86/util/intel-pt.c > +++ b/tools/perf/arch/x86/util/intel-pt.c > @@ -17,6 +17,7 @@ > #include "../../util/event.h" > #include "../../util/evlist.h" > #include "../../util/evsel.h" > +#include "../../util/evsel_config.h" > #include "../../util/cpumap.h" > #include "../../util/mmap.h" > #include <subcmd/parse-options.h> > @@ -551,6 +552,43 @@ static int intel_pt_validate_config(struct perf_pmu *intel_pt_pmu, > evsel->core.attr.config); > } > > +static void intel_pt_config_sample_mode(struct perf_pmu *intel_pt_pmu, > + struct evsel *evsel) > +{ > + struct perf_evsel_config_term *term; > + u64 user_bits = 0, bits; > + > + term = perf_evsel__get_config_term(evsel, CFG_CHG); > + if (term) > + user_bits = term->val.cfg_chg; > + > + bits = perf_pmu__format_bits(&intel_pt_pmu->format, "psb_period"); > + > + /* Did user change psb_period */ > + if (bits & user_bits) > + return; > + > + /* Set psb_period to 0 */ > + evsel->core.attr.config &= ~bits; > +} > + > +static void intel_pt_min_max_sample_sz(struct evlist *evlist, > + size_t *min_sz, size_t *max_sz) > +{ > + struct evsel *evsel; > + > + evlist__for_each_entry(evlist, evsel) { > + size_t sz = evsel->core.attr.aux_sample_size; > + > + if (!sz) > + continue; > + if (min_sz && (sz < *min_sz || !*min_sz)) > + *min_sz = sz; > + if (max_sz && sz > *max_sz) > + *max_sz = sz; > + } > +} > + > /* > * Currently, there is not enough information to disambiguate different PEBS > * events, so only allow one. > @@ -606,6 +644,11 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, > return -EINVAL; > } > > + if (opts->auxtrace_snapshot_mode && opts->auxtrace_sample_mode) { > + pr_err("Snapshot mode (" INTEL_PT_PMU_NAME " PMU) and sample trace cannot be used together\n"); > + return -EINVAL; > + } > + > if (opts->use_clockid) { > pr_err("Cannot use clockid (-k option) with " INTEL_PT_PMU_NAME "\n"); > return -EINVAL; > @@ -617,6 +660,9 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, > if (!opts->full_auxtrace) > return 0; > > + if (opts->auxtrace_sample_mode) > + intel_pt_config_sample_mode(intel_pt_pmu, intel_pt_evsel); > + > err = intel_pt_validate_config(intel_pt_pmu, intel_pt_evsel); > if (err) > return err; > @@ -666,6 +712,34 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, > opts->auxtrace_snapshot_size, psb_period); > } > > + /* Set default sizes for sample mode */ > + if (opts->auxtrace_sample_mode) { > + size_t psb_period = intel_pt_psb_period(intel_pt_pmu, evlist); > + size_t min_sz = 0, max_sz = 0; > + > + intel_pt_min_max_sample_sz(evlist, &min_sz, &max_sz); > + if (!opts->auxtrace_mmap_pages && !privileged && > + opts->mmap_pages == UINT_MAX) > + opts->mmap_pages = KiB(256) / page_size; > + if (!opts->auxtrace_mmap_pages) { > + size_t sz = round_up(max_sz, page_size) / page_size; > + > + opts->auxtrace_mmap_pages = roundup_pow_of_two(sz); > + } > + if (max_sz > opts->auxtrace_mmap_pages * (size_t)page_size) { > + pr_err("Sample size %zu must not be greater than AUX area tracing mmap size %zu\n", > + max_sz, > + opts->auxtrace_mmap_pages * (size_t)page_size); > + return -EINVAL; > + } > + pr_debug2("Intel PT min. sample size: %zu max. sample size: %zu\n", > + min_sz, max_sz); > + if (psb_period && > + min_sz <= psb_period + INTEL_PT_PSB_PERIOD_NEAR) > + ui__warning("Intel PT sample size (%zu) may be too small for PSB period (%zu)\n", > + min_sz, psb_period); > + } > + > /* Set default sizes for full trace mode */ > if (opts->full_auxtrace && !opts->auxtrace_mmap_pages) { > if (privileged) { > @@ -682,7 +756,7 @@ static int intel_pt_recording_options(struct auxtrace_record *itr, > size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size; > size_t min_sz; > > - if (opts->auxtrace_snapshot_mode) > + if (opts->auxtrace_snapshot_mode || opts->auxtrace_sample_mode) > min_sz = KiB(4); > else > min_sz = KiB(8); > @@ -1136,5 +1210,10 @@ struct auxtrace_record *intel_pt_recording_init(int *err) > ptr->itr.parse_snapshot_options = intel_pt_parse_snapshot_options; > ptr->itr.reference = intel_pt_reference; > ptr->itr.read_finish = intel_pt_read_finish; > + /* > + * Decoding starts at a PSB packet. Minimum PSB period is 2K so 4K > + * should give at least 1 PSB per sample. > + */ > + ptr->itr.default_aux_sample_size = 4096; > return &ptr->itr; > } > -- > 2.17.1
--
- Arnaldo
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