perf pmu: Lazily compute default config

The default config is computed during creation of the PMU and may do
things like scanning sysfs, when the PMU may just be used as part of
scanning. Change default_config to perf_event_attr_init_default, a
callback that is used when a default config needs initializing. This
avoids holding onto the memory for a perf_event_attr and copying.

On a tigerlake laptop running the pmu-scan benchmark:

Before:
Running 'internals/pmu-scan' benchmark:
Computing performance of sysfs PMU event scan for 100 times
  Average core PMU scanning took: 28.780 usec (+- 0.503 usec)
  Average PMU scanning took: 283.480 usec (+- 18.471 usec)
Number of openat syscalls: 30,227

After:
Running 'internals/pmu-scan' benchmark:
Computing performance of sysfs PMU event scan for 100 times
  Average core PMU scanning took: 27.880 usec (+- 0.169 usec)
  Average PMU scanning took: 245.260 usec (+- 15.758 usec)
Number of openat syscalls: 28,914

Over 3 runs it is a nearly 12% reduction in execution time and a 4.3%
of openat calls.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: James Clark <james.clark@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Will Deacon <will@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: John Garry <john.g.garry@oracle.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: coresight@lists.linaro.org
Link: https://lore.kernel.org/r/20231012175645.1849503-8-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index b8d6a953fd7423e161db97dec6b304d66fa17ee6..16bba74f048bfc3e0561471102b2d94d0608d66e 100644 (file)
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -917,16 +917,9 @@ out:
  * (CFG_CHG and evsel__set_config_if_unset()). If no default is set then user
  * changes aren't tracked.
  */
-struct perf_event_attr *
-cs_etm_get_default_config(struct perf_pmu *pmu __maybe_unused)
+void
+cs_etm_get_default_config(const struct perf_pmu *pmu __maybe_unused,
+                         struct perf_event_attr *attr)
 {
-       struct perf_event_attr *attr;
-
-       attr = zalloc(sizeof(struct perf_event_attr));
-       if (!attr)
-               return NULL;
-
        attr->sample_period = 1;
-
-       return attr;
 }

diff --git a/tools/perf/arch/arm/util/pmu.c b/tools/perf/arch/arm/util/pmu.c
index f25f68f84a949aa1182c325ac25eab8bfc34b8ca..7f3af3b97f3bac2a35faddc2a0a0ad180198a618 100644 (file)
--- a/tools/perf/arch/arm/util/pmu.c
+++ b/tools/perf/arch/arm/util/pmu.c
@@ -20,12 +20,12 @@ void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
        if (!strcmp(pmu->name, CORESIGHT_ETM_PMU_NAME)) {
                /* add ETM default config here */
                pmu->selectable = true;
-               pmu->default_config = cs_etm_get_default_config(pmu);
+               pmu->perf_event_attr_init_default = cs_etm_get_default_config;
 #if defined(__aarch64__)
        } else if (strstarts(pmu->name, ARM_SPE_PMU_NAME)) {
                pmu->selectable = true;
                pmu->is_uncore = false;
-               pmu->default_config = arm_spe_pmu_default_config(pmu);
+               pmu->perf_event_attr_init_default = arm_spe_pmu_default_config;
        } else if (strstarts(pmu->name, HISI_PTT_PMU_NAME)) {
                pmu->selectable = true;
 #endif

diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
index 08a76734ccd2ddb37e1d77e74aca5c756a659335..e3acc739bd0027b214a4aa5296e81bfcac3afba7 100644 (file)
--- a/tools/perf/arch/arm64/util/arm-spe.c
+++ b/tools/perf/arch/arm64/util/arm-spe.c
@@ -113,6 +113,25 @@ arm_spe_snapshot_resolve_auxtrace_defaults(struct record_opts *opts,
        }
 }
 
+static __u64 arm_spe_pmu__sample_period(const struct perf_pmu *arm_spe_pmu)
+{
+       static __u64 sample_period;
+
+       if (sample_period)
+               return sample_period;
+
+       /*
+        * If kernel driver doesn't advertise a minimum,
+        * use max allowable by PMSIDR_EL1.INTERVAL
+        */
+       if (perf_pmu__scan_file(arm_spe_pmu, "caps/min_interval", "%llu",
+                               &sample_period) != 1) {
+               pr_debug("arm_spe driver doesn't advertise a min. interval. Using 4096\n");
+               sample_period = 4096;
+       }
+       return sample_period;
+}
+
 static int arm_spe_recording_options(struct auxtrace_record *itr,
                                     struct evlist *evlist,
                                     struct record_opts *opts)
@@ -136,7 +155,7 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
                                return -EINVAL;
                        }
                        evsel->core.attr.freq = 0;
-                       evsel->core.attr.sample_period = arm_spe_pmu->default_config->sample_period;
+                       evsel->core.attr.sample_period = arm_spe_pmu__sample_period(arm_spe_pmu);
                        evsel->needs_auxtrace_mmap = true;
                        arm_spe_evsel = evsel;
                        opts->full_auxtrace = true;
@@ -495,26 +514,8 @@ struct auxtrace_record *arm_spe_recording_init(int *err,
        return &sper->itr;
 }
 
-struct perf_event_attr
-*arm_spe_pmu_default_config(struct perf_pmu *arm_spe_pmu)
+void
+arm_spe_pmu_default_config(const struct perf_pmu *arm_spe_pmu, struct perf_event_attr *attr)
 {
-       struct perf_event_attr *attr;
-
-       attr = zalloc(sizeof(struct perf_event_attr));
-       if (!attr) {
-               pr_err("arm_spe default config cannot allocate a perf_event_attr\n");
-               return NULL;
-       }
-
-       /*
-        * If kernel driver doesn't advertise a minimum,
-        * use max allowable by PMSIDR_EL1.INTERVAL
-        */
-       if (perf_pmu__scan_file(arm_spe_pmu, "caps/min_interval", "%llu",
-                                 &attr->sample_period) != 1) {
-               pr_debug("arm_spe driver doesn't advertise a min. interval. Using 4096\n");
-               attr->sample_period = 4096;
-       }
-
-       return attr;
+       attr->sample_period = arm_spe_pmu__sample_period(arm_spe_pmu);
 }

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
index 6d6cd8f9133cb1709e5456dd22b31b574f56fbe3..fa0c718b9e7277f0374356bf5d46b603f19ed7ca 100644 (file)
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -60,7 +60,7 @@ struct intel_pt_recording {
        size_t                          priv_size;
 };
 
-static int intel_pt_parse_terms_with_default(struct perf_pmu *pmu,
+static int intel_pt_parse_terms_with_default(const struct perf_pmu *pmu,
                                             const char *str,
                                             u64 *config)
 {
@@ -84,7 +84,7 @@ out_free:
        return err;
 }
 
-static int intel_pt_parse_terms(struct perf_pmu *pmu, const char *str, u64 *config)
+static int intel_pt_parse_terms(const struct perf_pmu *pmu, const char *str, u64 *config)
 {
        *config = 0;
        return intel_pt_parse_terms_with_default(pmu, str, config);
@@ -177,7 +177,7 @@ static int intel_pt_pick_bit(int bits, int target)
        return pick;
 }
 
-static u64 intel_pt_default_config(struct perf_pmu *intel_pt_pmu)
+static u64 intel_pt_default_config(const struct perf_pmu *intel_pt_pmu)
 {
        char buf[256];
        int mtc, mtc_periods = 0, mtc_period;
@@ -256,18 +256,17 @@ static int intel_pt_parse_snapshot_options(struct auxtrace_record *itr,
        return 0;
 }
 
-struct perf_event_attr *
-intel_pt_pmu_default_config(struct perf_pmu *intel_pt_pmu)
+void intel_pt_pmu_default_config(const struct perf_pmu *intel_pt_pmu,
+                                struct perf_event_attr *attr)
 {
-       struct perf_event_attr *attr;
+       static u64 config;
+       static bool initialized;
 
-       attr = zalloc(sizeof(struct perf_event_attr));
-       if (!attr)
-               return NULL;
-
-       attr->config = intel_pt_default_config(intel_pt_pmu);
-
-       return attr;
+       if (!initialized) {
+               config = intel_pt_default_config(intel_pt_pmu);
+               initialized = true;
+       }
+       attr->config = config;
 }
 
 static const char *intel_pt_find_filter(struct evlist *evlist,

diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index 949b3e2c67bdc52b05d4655d01d875e1baaa0805..469555ae9b3c2d77328e11ba27e575948611eeaa 100644 (file)
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c
@@ -23,7 +23,7 @@ void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
        if (!strcmp(pmu->name, INTEL_PT_PMU_NAME)) {
                pmu->auxtrace = true;
                pmu->selectable = true;
-               pmu->default_config = intel_pt_pmu_default_config(pmu);
+               pmu->perf_event_attr_init_default = intel_pt_pmu_default_config;
        }
        if (!strcmp(pmu->name, INTEL_BTS_PMU_NAME)) {
                pmu->auxtrace = true;

diff --git a/tools/perf/util/arm-spe.h b/tools/perf/util/arm-spe.h
index 98d3235781c3c0ffbfb5714eae259297d19ecbcb..4f4900c18f3e232bd02feb1341d321744cd19284 100644 (file)
--- a/tools/perf/util/arm-spe.h
+++ b/tools/perf/util/arm-spe.h
@@ -27,5 +27,7 @@ struct auxtrace_record *arm_spe_recording_init(int *err,
 int arm_spe_process_auxtrace_info(union perf_event *event,
                                  struct perf_session *session);
 
-struct perf_event_attr *arm_spe_pmu_default_config(struct perf_pmu *arm_spe_pmu);
+void arm_spe_pmu_default_config(const struct perf_pmu *arm_spe_pmu,
+                               struct perf_event_attr *attr);
+
 #endif

diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
index 7cca3788791760befb494ee0237cd09436576237..4696267a32f0c9caedc190c3b83443ab1ccb0907 100644 (file)
--- a/tools/perf/util/cs-etm.h
+++ b/tools/perf/util/cs-etm.h
@@ -242,7 +242,7 @@ struct cs_etm_packet_queue {
 
 int cs_etm__process_auxtrace_info(union perf_event *event,
                                  struct perf_session *session);
-struct perf_event_attr *cs_etm_get_default_config(struct perf_pmu *pmu);
+void cs_etm_get_default_config(const struct perf_pmu *pmu, struct perf_event_attr *attr);
 
 enum cs_etm_pid_fmt {
        CS_ETM_PIDFMT_NONE,

diff --git a/tools/perf/util/intel-pt.h b/tools/perf/util/intel-pt.h
index c7d6068e3a6bbd42dec3a7a807655f9aa57b2f8f..18fd0be52e6c367193a78a1b24d8ee52159dee84 100644 (file)
--- a/tools/perf/util/intel-pt.h
+++ b/tools/perf/util/intel-pt.h
@@ -42,6 +42,7 @@ struct auxtrace_record *intel_pt_recording_init(int *err);
 int intel_pt_process_auxtrace_info(union perf_event *event,
                                   struct perf_session *session);
 
-struct perf_event_attr *intel_pt_pmu_default_config(struct perf_pmu *pmu);
+void intel_pt_pmu_default_config(const struct perf_pmu *intel_pt_pmu,
+                                struct perf_event_attr *attr);
 
 #endif

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 23c027cf20aefedf1cc22cc3dbd51960f4b71f1d..aa2f5c6fc7fc24f205b9c88012dfd8016fdf9b3e 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1418,11 +1418,10 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
        }
        fix_raw(&parsed_terms, pmu);
 
-       if (pmu->default_config) {
-               memcpy(&attr, pmu->default_config, sizeof(struct perf_event_attr));
-       } else {
-               memset(&attr, 0, sizeof(attr));
-       }
+       memset(&attr, 0, sizeof(attr));
+       if (pmu->perf_event_attr_init_default)
+               pmu->perf_event_attr_init_default(pmu, &attr);
+
        attr.type = pmu->type;
 
        if (list_empty(&parsed_terms.terms)) {
@@ -1466,7 +1465,8 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
         * When using default config, record which bits of attr->config were
         * changed by the user.
         */
-       if (pmu->default_config && get_config_chgs(pmu, &parsed_terms, &config_terms)) {
+       if (pmu->perf_event_attr_init_default &&
+           get_config_chgs(pmu, &parsed_terms, &config_terms)) {
                parse_events_terms__exit(&parsed_terms);
                return -ENOMEM;
        }

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 8ef675ea7bdd4030c9e32e6cda90ac59603de63d..a967d25e899b731d9404142189d81f1ef818b0ca 100644 (file)
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1402,7 +1402,7 @@ int perf_pmu__config(struct perf_pmu *pmu, struct perf_event_attr *attr,
                     struct parse_events_terms *head_terms,
                     struct parse_events_error *err)
 {
-       bool zero = !!pmu->default_config;
+       bool zero = !!pmu->perf_event_attr_init_default;
 
        return perf_pmu__config_terms(pmu, attr, head_terms, zero, err);
 }
@@ -2064,7 +2064,6 @@ void perf_pmu__delete(struct perf_pmu *pmu)
 
        perf_cpu_map__put(pmu->cpus);
 
-       zfree(&pmu->default_config);
        zfree(&pmu->name);
        zfree(&pmu->alias_name);
        zfree(&pmu->id);

diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 5a05131aa4ce1876a58236c4eeb5141a0a643935..d2895d415f08fbf941bfd1bfa52f371307228e09 100644 (file)
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -92,10 +92,11 @@ struct perf_pmu {
         */
        int max_precise;
        /**
-        * @default_config: Optional default perf_event_attr determined in
-        * architecture specific code.
+        * @perf_event_attr_init_default: Optional function to default
+        * initialize PMU specific parts of the perf_event_attr.
         */
-       struct perf_event_attr *default_config;
+       void (*perf_event_attr_init_default)(const struct perf_pmu *pmu,
+                                            struct perf_event_attr *attr);
        /**
         * @cpus: Empty or the contents of either of:
         * <sysfs>/bus/event_source/devices/<name>/cpumask.