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Message-ID: <9cdc97eb-a194-454a-916c-2acf64f0c726@linaro.org>
Date: Wed, 4 Sep 2024 14:29:17 +0100
From: James Clark <james.clark@...aro.org>
To: Namhyung Kim <namhyung@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, linux-perf-users@...r.kernel.org,
Ravi Bangoria <ravi.bangoria@....com>, Mark Rutland <mark.rutland@....com>,
James Clark <james.clark@....com>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, Kajol Jain
<kjain@...ux.ibm.com>, Thomas Richter <tmricht@...ux.ibm.com>,
Atish Patra <atishp@...shpatra.org>, Palmer Dabbelt <palmer@...osinc.com>,
Mingwei Zhang <mizhang@...gle.com>, Ian Rogers <irogers@...gle.com>,
Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [PATCH 7/8] perf tools: Add fallback for exclude_guest
On 04/09/2024 2:28 pm, James Clark wrote:
>
>
> On 04/09/2024 7:41 am, Namhyung Kim wrote:
>> It seems Apple M1 PMU requires exclude_guest set and returns EOPNOTSUPP
>> if not. Let's add a fallback so that it can work with default events.
>>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: James Clark <james.clark@...aro.org>
>> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
>> ---
>> tools/perf/util/evsel.c | 21 +++++++++++++++++++++
>> 1 file changed, 21 insertions(+)
>>
>> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
>> index 0de0a72947db3f10..8c4d70f7b2f5b880 100644
>> --- a/tools/perf/util/evsel.c
>> +++ b/tools/perf/util/evsel.c
>> @@ -3400,6 +3400,27 @@ bool evsel__fallback(struct evsel *evsel,
>> struct target *target, int err,
>> "to fall back to excluding hypervisor samples",
>> paranoid);
>> evsel->core.attr.exclude_hv = 1;
>> + return true;
>> + } else if (err == EOPNOTSUPP && !evsel->core.attr.exclude_guest &&
>> + !evsel->exclude_GH) {
>> + const char *name = evsel__name(evsel);
>> + char *new_name;
>> + const char *sep = ":";
>> +
>> + /* Is there already the separator in the name. */
>> + if (strchr(name, '/') ||
>> + (strchr(name, ':') && !evsel->is_libpfm_event))
>> + sep = "";
>> +
>> + if (asprintf(&new_name, "%s%su", name, sep) < 0)
>> + return false;
>> +
>> + free(evsel->name);
>> + evsel->name = new_name;
>> + /* Apple M1 requires exclude_guest */
>> + scnprintf(msg, msgsize, "trying to fall back to excluding
>> guest samples");
>> + evsel->core.attr.exclude_guest = 1;
>> +
>> return true;
>> }
>
> Not sure if this is working, for some reason it doesn't try the
> fallback. With exclude guest made mandatory in the Arm PMU, then:
>
> $ perf stat -e cycles -vvv -- true
>
> Control descriptor is not initialized
> Opening: cycles
> ------------------------------------------------------------
> perf_event_attr:
> type 0 (PERF_TYPE_HARDWARE)
> size 136
> config 0xb00000000
> sample_type IDENTIFIER
> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> disabled 1
> inherit 1
> enable_on_exec 1
> ------------------------------------------------------------
> sys_perf_event_open: pid 698 cpu -1 group_fd -1 flags 0x8
> sys_perf_event_open failed, error -95
> Warning:
> cycles event is not supported by the kernel.
> Opening: cycles
> ------------------------------------------------------------
> perf_event_attr:
> type 0 (PERF_TYPE_HARDWARE)
> size 136
> config 0xa00000000
> sample_type IDENTIFIER
> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
> disabled 1
> inherit 1
> enable_on_exec 1
> ------------------------------------------------------------
> sys_perf_event_open: pid 698 cpu -1 group_fd -1 flags 0x8
> sys_perf_event_open failed, error -95
> Warning:
> cycles event is not supported by the kernel.
> failed to read counter cycles
> failed to read counter cycles
>
> Performance counter stats for 'true':
>
> <not supported> armv8_cortex_a53/cycles/
> <not supported> armv8_cortex_a57/cycles/
>
>
>
> Other than that, all the tests are passing on Juno (without the
> exclude_guest requirement).
Sorry one other thing, I think this commit would also need to come
before the change to the exclude_guest default to keep bisect working.
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