Kan Liang
8d7f85e323
The "perf all PMU test" fails on a Coffee Lake machine. The failure is caused by the below change in the commite2641db83f("perf vendor events: Add/update skylake events/metrics"). + { + "BriefDescription": "This 48-bit fixed counter counts the UCLK cycles", + "Counter": "FIXED", + "EventCode": "0xff", + "EventName": "UNC_CLOCK.SOCKET", + "PerPkg": "1", + "PublicDescription": "This 48-bit fixed counter counts the UCLK cycles.", + "Unit": "cbox_0" } The other cbox events have the unit name "CBOX", while the fixed counter has a unit name "cbox_0". So the events_table will maintain separate entries for cbox and cbox_0. The perf_pmus__print_pmu_events() calculates the total number of events, allocate an aliases buffer, store all the events into the buffer, sort, and print all the aliases one by one. The problem is that the calculated total number of events doesn't match the stored events in the aliases buffer. The perf_pmu__num_events() is used to calculate the number of events. It invokes the pmu_events_table__num_events() to go through the entire events_table to find all events. Because of the pmu_uncore_alias_match(), the suffix of uncore PMU will be ignored. So the events for cbox and cbox_0 are all counted. When storing events into the aliases buffer, the perf_pmu__for_each_event() only process the events for cbox. Since a bigger buffer was allocated, the last entry are all 0. When printing all the aliases, null will be outputted, and trigger the failure. The mismatch was introduced from the commite3edd6cf63("perf pmu-events: Reduce processed events by passing PMU"). The pmu_events_table__for_each_event() stops immediately once a pmu is set. But for uncore, especially this case, the method is wrong and mismatch what perf does in the perf_pmu__num_events(). With the patch, $ perf list pmu | grep -A 1 clock.socket unc_clock.socket [This 48-bit fixed counter counts the UCLK cycles. Unit: uncore_cbox_0 $ perf test "perf all PMU test" 107: perf all PMU test : Ok Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/all/202407101021.2c8baddb-oliver.sang@intel.com/ Fixes:e3edd6cf63("perf pmu-events: Reduce processed events by passing PMU") Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Reviewed-by: Ian Rogers <irogers@google.com> Cc: Sandipan Das <sandipan.das@amd.com> Cc: Benjamin Gray <bgray@linux.ibm.com> Cc: Xu Yang <xu.yang_2@nxp.com> Cc: John Garry <john.g.garry@oracle.com> Link: https://lore.kernel.org/r/20241001021431.814811-1-irogers@google.com Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.