From 8a3d2ee0de3828e0d01f9682d35ee53704659bd0 Mon Sep 17 00:00:00 2001 From: Zhengjun Xing Date: Fri, 18 Feb 2022 17:31:27 +0800 Subject: [PATCH] perf evlist: Fix failed to use cpu list for uncore events The 'perf record' and 'perf stat' commands have supported the option '-C/--cpus' to count or collect only on the list of CPUs provided. Commit 1d3351e631fc34d7 ("perf tools: Enable on a list of CPUs for hybrid") add it to be supported for hybrid. For hybrid support, it checks the cpu list are available on hybrid PMU. But when we test only uncore events(or events not in cpu_core and cpu_atom), there is a bug: Before: # perf stat -C0 -e uncore_clock/clockticks/ sleep 1 failed to use cpu list 0 In this case, for uncore event, its pmu_name is not cpu_core or cpu_atom, so in evlist__fix_hybrid_cpus, perf_pmu__find_hybrid_pmu should return NULL,both events_nr and unmatched_count should be 0 ,then the cpu list check function evlist__fix_hybrid_cpus return -1 and the error "failed to use cpu list 0" will happen. Bypass "events_nr=0" case then the issue is fixed. After: # perf stat -C0 -e uncore_clock/clockticks/ sleep 1 Performance counter stats for 'CPU(s) 0': 195,476,873 uncore_clock/clockticks/ 1.004518677 seconds time elapsed When testing with at least one core event and uncore events, it has no issue. # perf stat -C0 -e cpu_core/cpu-cycles/,uncore_clock/clockticks/ sleep 1 Performance counter stats for 'CPU(s) 0': 5,993,774 cpu_core/cpu-cycles/ 301,025,912 uncore_clock/clockticks/ 1.003964934 seconds time elapsed Fixes: 1d3351e631fc34d7 ("perf tools: Enable on a list of CPUs for hybrid") Reviewed-by: Kan Liang Signed-off-by: Zhengjun Xing Cc: Adrian Hunter Cc: alexander.shishkin@intel.com Cc: Andi Kleen Cc: Ian Rogers Cc: Jin Yao Cc: Jiri Olsa Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/20220218093127.1844241-1-zhengjun.xing@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist-hybrid.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/evlist-hybrid.c b/tools/perf/util/evlist-hybrid.c index 7f23421..57f02be 100644 --- a/tools/perf/util/evlist-hybrid.c +++ b/tools/perf/util/evlist-hybrid.c @@ -154,8 +154,8 @@ int evlist__fix_hybrid_cpus(struct evlist *evlist, const char *cpu_list) perf_cpu_map__put(matched_cpus); perf_cpu_map__put(unmatched_cpus); } - - ret = (unmatched_count == events_nr) ? -1 : 0; + if (events_nr) + ret = (unmatched_count == events_nr) ? -1 : 0; out: perf_cpu_map__put(cpus); return ret; -- 2.7.4