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Message-ID: <CAP-5=fVU_ngSOsDs_9Ma=pyOPzD3jr-MYQC9LeAirR--bfA-BQ@mail.gmail.com>
Date: Thu, 22 Aug 2024 08:15:05 -0700
From: Ian Rogers <irogers@...gle.com>
To: Jon Kohler <jon@...anix.com>
Cc: "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
Kan Liang <kan.liang@...ux.intel.com>,
"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>
Subject: Re: Perf test failures for 10.2 PMU event map aliases
On Thu, Aug 22, 2024 at 8:01 AM Jon Kohler <jon@...anix.com> wrote:
>
>
>
> > On Aug 20, 2024, at 11:17 AM, Ian Rogers <irogers@...gle.com> wrote:
> >
> > !-------------------------------------------------------------------|
> > CAUTION: External Email
> >
> > |-------------------------------------------------------------------!
> >
> > On Tue, Aug 20, 2024 at 6:54 AM Jon Kohler <jon@...anix.com> wrote:
> >>
> >>
> >>
> >>> On Aug 20, 2024, at 1:41 AM, Ian Rogers <irogers@...gle.com> wrote:
> >>>
> >>> !-------------------------------------------------------------------|
> >>> CAUTION: External Email
> >>>
> >>> |-------------------------------------------------------------------!
> >>>
> >>> On Mon, Aug 19, 2024 at 7:06 PM Jon Kohler <jon@...anix.com> wrote:
> >>>>
> >>>> Reaching out to the perf community for feedback on the following
> >>>> observed test failure. On 6.6.y, I see persistent failures with test
> >>>> 10.2 PMU event map aliases, complaining about testing aliases uncore
> >>>> PMU mismatches. I've included two outputs below, one with a bit of
> >>>> hacky print debugging.
> >>>>
> >>>> Using Intel(R) Xeon(R) Gold 6154 CPU:
> >>>> 10.2: PMU event map aliases :
> >>>> --- start ---
> >>>> test child forked, pid 962901
> >>>> Using CPUID GenuineIntel-6-55-4
> >>>
> >>> Hi Jon,
> >>>
> >>> Sorry for the brief reply but I thought some quick hints might unblock
> >>> you on this. The CPUID lines up with a SkylakeX:
> >>> https://urldefense.proofpoint.com/v2/url?u=https-3A__git.kernel.org_pub_scm_linux_kernel_git_perf_perf-2Dtools-2Dnext.git_tree_tools_perf_pmu-2Devents_arch_x86_mapfile.csv-3Fh-3Dperf-2Dtools-2Dnext-23n33&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=NGPRGGo37mQiSXgHKm5rCQ&m=RJx661xzakrB42hsUsFD1HhJczkgpaYur9lHVtl7j36__CBOqYfKf4Dnq0xdpBZl&s=F-eXsmTASgRsptt5Gahro6fRyMwEQdjZ6PtY7vhzIKM&e=
> >>>
> >>>> testing core PMU cpu aliases: pass
> >>>> JKDBG: pmu nr total 3 pmu->sysfs_aliases 3 pmu->sys_json_aliases 0
> >>>> JKDBG: pmu cpu_aliases_added nr total 4 pmu->cpu_json_aliases 1
> >>>> testing aliases uncore PMU uncore_imc_0: mismatch expected aliases
> >>>> (1) vs found (4)
> >>>> test child finished with -1
> >>>> ---- end ----
> >>>> PMU events subtest 2: FAILED!
> >>>>
> >>>> Using Intel(R) Xeon(R) Platinum 8352Y:
> >>>> 10.2: PMU event map aliases :
> >>>> --- start ---
> >>>> test child forked, pid 1765070
> >>>> Using CPUID GenuineIntel-6-6A-6
> >>>
> >>> This is an IcelakeX:
> >>> https://urldefense.proofpoint.com/v2/url?u=https-3A__git.kernel.org_pub_scm_linux_kernel_git_perf_perf-2Dtools-2Dnext.git_tree_tools_perf_pmu-2Devents_arch_x86_mapfile.csv-3Fh-3Dperf-2Dtools-2Dnext-23n18&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=NGPRGGo37mQiSXgHKm5rCQ&m=RJx661xzakrB42hsUsFD1HhJczkgpaYur9lHVtl7j36__CBOqYfKf4Dnq0xdpBZl&s=6DwD4ZmywAtcwCnRjx7wRfmdW_G65wHIuyZJIc__2yc&e=
> >>>
> >>>> testing core PMU cpu aliases: pass
> >>>> testing aliases uncore PMU uncore_imc_free_running_0: mismatch
> >>>> expected aliases (1) vs found (6)
> >>>> test child finished with -1
> >>>> ---- end ----
> >>>> PMU events subtest 2: FAILED!
> >>>>
> >>>> Digging in more, looking at pmu_aliases_parse, I see that we'll discard
> >>>> scale and unit files in pmu_alias_info_file, which leaves us with 3x
> >>>> aliases in the uncore_imc_0 in the first case and 5x aliases in the
> >>>> uncore_imc_free_running_0 second case.
> >>>>
> >>>> # From 6154-based system:
> >>>> ls -lhat /sys/devices/uncore_imc_0/events
> >>>
> >>> The "uncore_" prefix and the "_0" suffix are optional, the naming
> >>> matching is case insensitive. In the event json the events are listed
> >>> here:
> >>> https://urldefense.proofpoint.com/v2/url?u=https-3A__git.kernel.org_pub_scm_linux_kernel_git_perf_perf-2Dtools-2Dnext.git_tree_tools_perf_pmu-2Devents_arch_x86_skylakex_uncore-2Dmemory.json-3Fh-3Dperf-2Dtools-2Dnext&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=NGPRGGo37mQiSXgHKm5rCQ&m=RJx661xzakrB42hsUsFD1HhJczkgpaYur9lHVtl7j36__CBOqYfKf4Dnq0xdpBZl&s=FpAgVwLmTyXUFQIMZ_gbPlH9aXvrmcJ8CZaW3tKIaj4&e=
> >>>
> >>>> total 0
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 18:50 cas_count_read.scale
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 18:50 cas_count_read.unit
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 18:50 cas_count_write.scale
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 18:50 cas_count_write.unit
> >>>> -r--r--r--. 1 root root 4.0K Aug 9 15:30 cas_count_read
> >>>> -r--r--r--. 1 root root 4.0K Aug 9 15:30 cas_count_write
> >>>> -r--r--r--. 1 root root 4.0K Aug 9 15:30 clockticks
> >>>
> >>> This should be 3 sysfs events (I don't like the term alias), note that
> >>> we load the sysfs and json events lazily to avoid overhead.
> >>>
> >>>> drwxr-xr-x. 2 root root 0 Jul 17 03:40 .
> >>>> drwxr-xr-x. 5 root root 0 Jul 17 02:52 ..
> >>>>
> >>>> # From the 8352Y-based system:
> >>>> ls -lhat /sys/bus/event_source/devices/uncore_imc_free_running_0/events
> >>>> total 0
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 ddrt_read.scale
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 ddrt_read.unit
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 ddrt_write.scale
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 ddrt_write.unit
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 read.scale
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 read.unit
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 write.scale
> >>>> -r--r--r--. 1 root root 4.0K Aug 20 01:44 write.unit
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 21:33 dclk
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 21:33 ddrt_read
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 21:33 ddrt_write
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 21:33 read
> >>>> -r--r--r--. 1 root root 4.0K Aug 19 21:33 write
> >>>
> >>> This is 5 sysfs events, the json events are here:
> >>> https://urldefense.proofpoint.com/v2/url?u=https-3A__git.kernel.org_pub_scm_linux_kernel_git_perf_perf-2Dtools-2Dnext.git_tree_tools_perf_pmu-2Devents_arch_x86_icelakex_uncore-2Dmemory.json-3Fh-3Dperf-2Dtools-2Dnext-23n134&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=NGPRGGo37mQiSXgHKm5rCQ&m=RJx661xzakrB42hsUsFD1HhJczkgpaYur9lHVtl7j36__CBOqYfKf4Dnq0xdpBZl&s=MrHuUCZFqrNrd05IPyq4fuZDH4_owkEw0xHcc7bvGvU&e=
> >>> Note, the "Unit", meaning the PMU should be imc_free_running to match
> >>> this device.
> >>>
> >>>> drwxr-xr-x. 2 root root 0 Aug 15 03:15 .
> >>>> drwxr-xr-x. 5 root root 0 Aug 15 02:42 ..
> >>>>
> >>>> Looking at the structure of __test_uncore_pmu_event_aliases, however,
> >>>> I'm not quite sure how this is supposed to work. I've annotated a walk
> >>>> through below to highlight where things are going off the rails.
> >>>>
> >>>> static int __test_uncore_pmu_event_aliases(struct perf_pmu_test_pmu *test_pmu)
> >>>> {
> >>>> ...
> >>>> /* Count how many aliases we generated */
> >>>> alias_count = perf_pmu__num_events(pmu);
> >>>> // alias_count == 4 in the 6154-based system
> >>>> // alias_count == 6 in the 8352Y-based system
> >>>>
> >>>> /* Count how many aliases we expect from the known table */
> >>>> for (table = &test_pmu->aliases[0]; *table; table++)
> >>>> to_match_count++;
> >>>> // this is looking at aliases in struct perf_pmu_test_pmu
> >>>> // table, which for uncore_imc_0 is a single entry for
> >>>> // &uncore_imc_cache_hits.
> >>>> //
> >>>> // for the 8352Y case, likewise, we only have a single alias
> >>>> // in the table for &uncore_imc_free_running_cache_miss.
> >>>> //
> >>>> // in both cases, to_match_count == 1
> >>>>
> >>>> // Compare 4 vs 1 or 6 vs 1
> >>>> if (alias_count != to_match_count) {
> >>>> pr_debug("testing aliases uncore PMU %s: mismatch expected aliases (%d) vs found (%d)\n",
> >>>> pmu_name, to_match_count /* 1 */, alias_count /* 4 */);
> >>>> return -1;
> >>>> // we seemed doomed to hit this conditional always, no?
> >>>> }
> >>>> ...
> >>>> }
> >>>>
> >>>> I did a walkthrough of the latest mainline code, and don't see a marked
> >>>> difference that jump off the page to me that'd correct this behavior,
> >>>> and would love a helping hand to point in the right direction on this.
> >>>>
> >>>> What am I missing here?
> >>>
> >>> I'll need some more time to dig into this. Hopefully the pointers above help.
> >>
> >> Thanks for the quick reply and pointers, I appreciate it. The tricky bit still
> >> remains, as the code I posted to above seems to solely depend on the
> >> info filled into struct perf_pmu_test_pmu, right? If so, I don’t see how the
> >> dots connect from this test to the other events in sysfs/json’s.
> >
> > So looking at the test it is using the testcpu:
> > https://urldefense.proofpoint.com/v2/url?u=https-3A__git.kernel.org_pub_scm_linux_kernel_git_perf_perf-2Dtools-2Dnext.git_tree_tools_perf_tests_pmu-2Devents.c-3Fh-3Dperf-2Dtools-2Dnext-23n602&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=NGPRGGo37mQiSXgHKm5rCQ&m=upMgwNSdGAw5sdDUTdoyvXhLy4KhFUYqPdxZKx8Ov-ZxDYERFVy8PU040wwDAYPp&s=erGg8kUByjl_j5R0D0PxRZjTZhvazxwC9KW8rOT9Pp4&e=
> > the json for that is here:
> > https://urldefense.proofpoint.com/v2/url?u=https-3A__git.kernel.org_pub_scm_linux_kernel_git_perf_perf-2Dtools-2Dnext.git_tree_tools_perf_pmu-2Devents_arch_test_test-5Fsoc_cpu-3Fh-3Dperf-2Dtools-2Dnext&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=NGPRGGo37mQiSXgHKm5rCQ&m=upMgwNSdGAw5sdDUTdoyvXhLy4KhFUYqPdxZKx8Ov-ZxDYERFVy8PU040wwDAYPp&s=z535_TbF_oJLjEoRuhbbqzB9Xo5MwWWmOcP0pgMulWY&e=
> > The names in the test are based on ones seen on real CPUs, so this may
> > be leading to the confusion.
>
> Hey Ian,
> I was able to debug this a bit more. The following diff fixes this test on my system.
>
> Even though we were supposed to be using the test data only, the sysfs entries
> from my systems, which happened to have similar names, threw a wrench in
> this test.
>
> With this diff, we just use the JSON aliases that were added.
>
> Happy to send this out as a formal patch, but wanted to get the list’s 2cents
> first, as I feel like I’m missing something :)
>
> Jon
>
> diff --git a/tools/perf/tests/pmu-events.c b/tools/perf/tests/pmu-events.c
> index f5321fbdee79..893dc7afee76 100644
> --- a/tools/perf/tests/pmu-events.c
> +++ b/tools/perf/tests/pmu-events.c
> @@ -584,6 +584,9 @@ static int __test_uncore_pmu_event_aliases(struct perf_pmu_test_pmu *test_pmu)
> const struct pmu_events_table *events_table;
> int res = 0;
>
> + /* CPU events come from struct pmu_event pmu_events__test_soc_cpu
> + * and sys events come from struct pmu_event pmu_events__test_soc_sys
> + */
> events_table = find_core_events_table("testarch", "testcpu");
> if (!events_table)
> return -1;
> @@ -593,10 +596,14 @@ static int __test_uncore_pmu_event_aliases(struct perf_pmu_test_pmu *test_pmu)
> pmu->sysfs_aliases_loaded = true;
> pmu_add_sys_aliases(pmu);
>
> - /* Count how many aliases we generated */
> - alias_count = perf_pmu__num_events(pmu);
> + /* How many events we gathered for this PMU in test_soc.
> + * Note: we specifically do not use perf_pmu__num_events as that may
> + * include spurious system events from the system under test, which
> + * may have similarly named PMUs.
Thanks Jon, should we just rename the PMUs in the test json files? For
example, rather than "CBO" here:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/pmu-events/arch/test/test_soc/cpu/uncore.json?h=perf-tools-next#n10
we can have "test_pmu1".
Thanks for investigating this!
Ian
> + */
> + alias_count = pmu->cpu_json_aliases + pmu->sys_json_aliases;
>
> - /* Count how many aliases we expect from the known table */
> + /* How many aliases we expect from struct perf_pmu_test_pmu test_pmus */
> for (table = &test_pmu->aliases[0]; *table; table++)
> to_match_count++;
>
> >
> > Thanks,
> > Ian
>
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