From a1bf23052bdfe30ec3c693cf32feb2d79114ac16 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Fri, 15 Jan 2021 16:11:39 +0900 Subject: [PATCH] perf stat: Take cgroups into account for shadow stats As of now it doesn't consider cgroups when collecting shadow stats and metrics so counter values from different cgroups will be saved in a same slot. This resulted in incorrect numbers when those cgroups have different workloads. For example, let's look at the scenario below: cgroups A and C runs same workload which burns a cpu while cgroup B runs a light workload. $ perf stat -a -e cycles,instructions --for-each-cgroup A,B,C sleep 1 Performance counter stats for 'system wide': 3,958,116,522 cycles A 6,722,650,929 instructions A # 2.53 insn per cycle 1,132,741 cycles B 571,743 instructions B # 0.00 insn per cycle 4,007,799,935 cycles C 6,793,181,523 instructions C # 2.56 insn per cycle 1.001050869 seconds time elapsed When I run 'perf stat' with single workload, it usually shows IPC around 1.7. We can verify it (6,722,650,929.0 / 3,958,116,522 = 1.698) for cgroup A. But in this case, since cgroups are ignored, cycles are averaged so it used the lower value for IPC calculation and resulted in around 2.5. avg cycle: (3958116522 + 1132741 + 4007799935) / 3 = 2655683066 IPC (A) : 6722650929 / 2655683066 = 2.531 IPC (B) : 571743 / 2655683066 = 0.0002 IPC (C) : 6793181523 / 2655683066 = 2.557 We can simply compare cgroup pointers in the evsel and it'll be NULL when cgroups are not specified. With this patch, I can see correct numbers like below: $ perf stat -a -e cycles,instructions --for-each-cgroup A,B,C sleep 1 Performance counter stats for 'system wide': 4,171,051,687 cycles A 7,219,793,922 instructions A # 1.73 insn per cycle 1,051,189 cycles B 583,102 instructions B # 0.55 insn per cycle 4,171,124,710 cycles C 7,192,944,580 instructions C # 1.72 insn per cycle 1.007909814 seconds time elapsed Signed-off-by: Namhyung Kim Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Andi Kleen Cc: Ian Rogers Cc: Jin Yao Cc: Mark Rutland Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lore.kernel.org/lkml/20210115071139.257042-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/stat-shadow.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c index a1565b6..12eafd1 100644 --- a/tools/perf/util/stat-shadow.c +++ b/tools/perf/util/stat-shadow.c @@ -8,6 +8,7 @@ #include "evlist.h" #include "expr.h" #include "metricgroup.h" +#include "cgroup.h" #include /* @@ -28,6 +29,7 @@ struct saved_value { enum stat_type type; int ctx; int cpu; + struct cgroup *cgrp; struct runtime_stat *stat; struct stats stats; u64 metric_total; @@ -57,6 +59,9 @@ static int saved_value_cmp(struct rb_node *rb_node, const void *entry) if (a->ctx != b->ctx) return a->ctx - b->ctx; + if (a->cgrp != b->cgrp) + return (char *)a->cgrp < (char *)b->cgrp ? -1 : +1; + if (a->evsel == NULL && b->evsel == NULL) { if (a->stat == b->stat) return 0; @@ -100,7 +105,8 @@ static struct saved_value *saved_value_lookup(struct evsel *evsel, bool create, enum stat_type type, int ctx, - struct runtime_stat *st) + struct runtime_stat *st, + struct cgroup *cgrp) { struct rblist *rblist; struct rb_node *nd; @@ -110,6 +116,7 @@ static struct saved_value *saved_value_lookup(struct evsel *evsel, .type = type, .ctx = ctx, .stat = st, + .cgrp = cgrp, }; rblist = &st->value_list; @@ -197,6 +204,7 @@ void perf_stat__reset_shadow_per_stat(struct runtime_stat *st) struct runtime_stat_data { int ctx; + struct cgroup *cgrp; }; static void update_runtime_stat(struct runtime_stat *st, @@ -205,7 +213,7 @@ static void update_runtime_stat(struct runtime_stat *st, struct runtime_stat_data *rsd) { struct saved_value *v = saved_value_lookup(NULL, cpu, true, type, - rsd->ctx, st); + rsd->ctx, st, rsd->cgrp); if (v) update_stats(&v->stats, count); @@ -223,6 +231,7 @@ void perf_stat__update_shadow_stats(struct evsel *counter, u64 count, struct saved_value *v; struct runtime_stat_data rsd = { .ctx = evsel_context(counter), + .cgrp = counter->cgrp, }; count *= counter->scale; @@ -290,13 +299,14 @@ void perf_stat__update_shadow_stats(struct evsel *counter, u64 count, update_runtime_stat(st, STAT_APERF, cpu, count, &rsd); if (counter->collect_stat) { - v = saved_value_lookup(counter, cpu, true, STAT_NONE, 0, st); + v = saved_value_lookup(counter, cpu, true, STAT_NONE, 0, st, + rsd.cgrp); update_stats(&v->stats, count); if (counter->metric_leader) v->metric_total += count; } else if (counter->metric_leader) { v = saved_value_lookup(counter->metric_leader, - cpu, true, STAT_NONE, 0, st); + cpu, true, STAT_NONE, 0, st, rsd.cgrp); v->metric_total += count; v->metric_other++; } @@ -438,7 +448,7 @@ static double runtime_stat_avg(struct runtime_stat *st, { struct saved_value *v; - v = saved_value_lookup(NULL, cpu, false, type, rsd->ctx, st); + v = saved_value_lookup(NULL, cpu, false, type, rsd->ctx, st, rsd->cgrp); if (!v) return 0.0; @@ -451,7 +461,7 @@ static double runtime_stat_n(struct runtime_stat *st, { struct saved_value *v; - v = saved_value_lookup(NULL, cpu, false, type, rsd->ctx, st); + v = saved_value_lookup(NULL, cpu, false, type, rsd->ctx, st, rsd->cgrp); if (!v) return 0.0; @@ -805,7 +815,8 @@ static int prepare_metric(struct evsel **metric_events, scale = 1e-9; } else { v = saved_value_lookup(metric_events[i], cpu, false, - STAT_NONE, 0, st); + STAT_NONE, 0, st, + metric_events[i]->cgrp); if (!v) break; stats = &v->stats; @@ -933,6 +944,7 @@ void perf_stat__print_shadow_stats(struct perf_stat_config *config, const char *color = NULL; struct runtime_stat_data rsd = { .ctx = evsel_context(evsel), + .cgrp = evsel->cgrp, }; struct metric_event *me; int num = 1; -- 2.7.4