Messages in this thread | | | From | Ian Rogers <> | Date | Tue, 12 Dec 2023 14:12:27 -0800 | Subject | Re: [PATCH V2] perf top: Use evsel's cpus to replace user_requested_cpus |
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On Tue, Dec 12, 2023 at 1:25 PM Liang, Kan <kan.liang@linux.intel.com> wrote: > > > > On 2023-12-12 3:37 p.m., Ian Rogers wrote: > > On Tue, Dec 12, 2023 at 11:39 AM <kan.liang@linux.intel.com> wrote: > >> > >> 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 perf top expects that the "cycles" is collected on all CPUs in the > >> system. But for hybrid there is no single "cycles" event which can cover > >> all CPUs. Perf has to split it into two cycles events, e.g., > >> 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 of the above error out. > >> > >> Perf should only open the cycles event on the corresponding CPU. The > >> commit ef91871c960e ("perf evlist: Propagate user CPU maps intersecting > >> core PMU maps") 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 are also propagated to the evsel's threads in > >> __perf_evlist__propagate_maps(). For a system-wide event, perf appends > >> a dummy event and assign it to the evsel's threads. For a per-thread > >> event, the evlist's thread_map is assigned to the evsel's threads. The > >> same as the other tools, e.g., perf record, using the evsel's threads > >> when opening an event. > >> > >> Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org> > >> Closes: https://lore.kernel.org/linux-perf-users/ZXNnDrGKXbEELMXV@kernel.org/ > >> Reviewed-by: Ian Rogers <irogers@google.com> > >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> > >> --- > >> > >> Changes since V1: > >> - Update the description > >> - Add Reviewed-by from Ian > > > > Thanks Kan, quick question. Does "perf top" on hybrid ask the user to > > select between the cycles event on cpu_atom and cpu_core? > > Yes, but the event doesn't include the PMU information. > We probably need a follow up patch to append the PMU name. > > Available samples > 385 cycles:P > > 903 cycles:P
Thanks and agreed, it isn't possible to tell which is which PMU/CPU type at the moment. I tried the patch with perf top --stdio, there wasn't a choice of event and I can't tell what counter is being displayed. When I quit I also see: ``` exiting. corrupted double-linked list Aborted (core dumped) ``` but I wasn't able to repro this on a debuggable binary/system.
If my memory serves there was a patch where perf top was showing >1 event. It would be nice here to do some kind of hybrid merging rather than having to view each PMU's top separately.
Thanks, Ian
> Thanks, > Kan > > > I'm > > wondering if there is some kind of missing "hybrid-merge" > > functionality like we have for perf stat. > > > > Thanks, > > Ian > > > >> 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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