Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 12 Dec 2023 17:06:37 -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 2:12 PM Ian Rogers <irogers@google.com> wrote: > > 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.
Using event groups, but I noticed you removed the --group option. Maybe perf top can just use `{ ... }` notation for explicit grouping, but it might be implicit like in the hybrid case.
Thanks, Namhyung
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