Messages in this thread | | | Date | Tue, 12 Dec 2023 10:56:15 -0500 | Subject | Re: [PATCH] perf top: Use evsel's cpus to replace user_requested_cpus | From | "Liang, Kan" <> |
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On 2023-12-11 4:13 p.m., Arnaldo Carvalho de Melo wrote: > Em Fri, Dec 08, 2023 at 01:08:55PM -0800, kan.liang@linux.intel.com escreveu: >> From: Kan Liang <kan.liang@linux.intel.com> >> >> perf top errors out on a hybrid machine >> $perf top >> >> Error: >> The cycles:P event is not supported. >> >> The user_requested_cpus may contain CPUs that are invalid for a hybrid >> PMU. It causes perf_event_open to fail. > > ? > > All perf top expects is that the "cycles", the most basic one, be > collected, on all CPUs in the system. >
Yes, but for hybrid there is no single "cycles" event which can cover all CPUs. Perf has to split it into two cycles events, cpu_core/cycles/ and cpu_atom/cycles/. Each event has its own CPU mask. If a event is opened on the unsupported CPU. The open fails. That's the reason perf top fails. So perf should only open the cycles event on the corresponding CPU.
>> The commit ef91871c960e ("perf evlist: Propagate user CPU maps >> intersecting core PMU maps") already intersect the requested CPU map >> with the CPU map of the PMU. Use the evsel's cpus to replace >> user_requested_cpus. > >> The evlist's threads is also propagated to evsel's threads in >> __perf_evlist__propagate_maps(). Replace it as well. > > Thanks, but please try to add more detail to the fix so as to help > others to consider looking at the patch.
OK. For the threads, the same as other tools, e.g., perf record, perf appends a dummy for the system wide event. For a per-thread event, the evlist's thread_map is assigned to the evsel. So using the evsel's threads is appropriate and also be consistent with other tools.
I will update the description and send a V2.
Thanks, Kan
> > - Arnaldo > >> Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org> >> Closes: https://lore.kernel.org/linux-perf-users/ZXNnDrGKXbEELMXV@kernel.org/ >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> >> --- >> tools/perf/builtin-top.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c >> index ea8c7eca5eee..cce9350177e2 100644 >> --- a/tools/perf/builtin-top.c >> +++ b/tools/perf/builtin-top.c >> @@ -1027,8 +1027,8 @@ static int perf_top__start_counters(struct perf_top *top) >> >> evlist__for_each_entry(evlist, counter) { >> try_again: >> - if (evsel__open(counter, top->evlist->core.user_requested_cpus, >> - top->evlist->core.threads) < 0) { >> + if (evsel__open(counter, counter->core.cpus, >> + counter->core.threads) < 0) { >> >> /* >> * Specially handle overwrite fall back. >> -- >> 2.35.1 >> >
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