| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <65A24EAA-A348-4E77-AF5B-933B41C9CAB6@nutanix.com>
Date: Tue, 20 Aug 2024 13:54:41 +0000
From: Jon Kohler <jon@...anix.com>
To: Ian Rogers <irogers@...gle.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 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.
>
> Thanks,
> Ian
Powered by blists - more mailing lists