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 + +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 @@ -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; }