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SubjectRe: [PATCH V2 02/12] perf record: Support new sample type for data page size
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On 12/7/2020 12:07 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Nov 30, 2020 at 09:27:53AM -0800, kan.liang@linux.intel.com escreveu:
>> From: Kan Liang <kan.liang@linux.intel.com>
>>
>> Support new sample type PERF_SAMPLE_DATA_PAGE_SIZE for page size.
>>
>> Add new option --data-page-size to record sample data page size.
>
> So, trying this on a kernel without this feature I get:
>
> [acme@five perf]$ perf record --data-page-size sleep 1
> Error:
> The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles:u).
> /bin/dmesg | grep -i perf may provide additional information.
>
> [acme@five perf]$
>
> I'm adding the following patch right after yours, next time please test
> this and provide a similar error message.
>

Sorry, I missed it.

Besides the PERF_SAMPLE_DATA_PAGE_SIZE, I think we have to fix the
PERF_SAMPLE_CODE_PAGE_SIZE as well.
Should I send a separate patch to fix it?

Thanks,
Kan


> - Arnaldo
>
> commit 2044fec7fcc6070b09f9b6a67922b0b9e4295dba
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Mon Dec 7 14:04:05 2020 -0300
>
> perf evsel: Emit warning about kernel not supporting the data page size sample_type bit
>
> Before we had this unhelpful message:
>
> $ perf record --data-page-size sleep 1
> Error:
> The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles:u).
> /bin/dmesg | grep -i perf may provide additional information.
> $
>
> Add support to the perf_missing_features variable to remember what
> caused evsel__open() to fail and then use that information in
> evsel__open_strerror().
>
> $ perf record --data-page-size sleep 1
> Error:
> Asking for the data page size isn't supported by this kernel.
> $
>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Jiri Olsa <jolsa@redhat.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Stephane Eranian <eranian@google.com>
> Cc: Will Deacon <will@kernel.org>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 5e6085c3fc761a55..c26ea82220bd8625 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1873,7 +1873,12 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
> * Must probe features in the order they were added to the
> * perf_event_attr interface.
> */
> - if (!perf_missing_features.cgroup && evsel->core.attr.cgroup) {
> + if (!perf_missing_features.data_page_size &&
> + (evsel->core.attr.sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)) {
> + perf_missing_features.data_page_size = true;
> + pr_debug2_peo("Kernel has no PERF_SAMPLE_DATA_PAGE_SIZE support, bailing out\n");
> + goto out_close;
> + } else if (!perf_missing_features.cgroup && evsel->core.attr.cgroup) {
> perf_missing_features.cgroup = true;
> pr_debug2_peo("Kernel has no cgroup sampling support, bailing out\n");
> goto out_close;
> @@ -2673,6 +2678,8 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
> "We found oprofile daemon running, please stop it and try again.");
> break;
> case EINVAL:
> + if (evsel->core.attr.sample_type & PERF_SAMPLE_DATA_PAGE_SIZE && perf_missing_features.data_page_size)
> + return scnprintf(msg, size, "Asking for the data page size isn't supported by this kernel.");
> if (evsel->core.attr.write_backward && perf_missing_features.write_backward)
> return scnprintf(msg, size, "Reading from overwrite event is not supported by this kernel.");
> if (perf_missing_features.clockid)
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index 79a860d8e3eefe23..cd1d8dd431997b84 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -144,6 +144,7 @@ struct perf_missing_features {
> bool aux_output;
> bool branch_hw_idx;
> bool cgroup;
> + bool data_page_size;
> };
>
> extern struct perf_missing_features perf_missing_features;
>

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