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On hybrid platform, such as Alderlake, if atom CPUs are offlined, the kernel still exports the sysfs path '/sys/devices/cpu_atom/' for 'cpu_atom' pmu but the file '/sys/devices/cpu_atom/cpus' is empty, which indicates this is an invalid pmu. Need to check and skip the invalid hybrid pmu. Before: # perf list ... branch-instructions OR cpu_atom/branch-instructions/ [Kernel PMU event] branch-instructions OR cpu_core/branch-instructions/ [Kernel PMU event] branch-misses OR cpu_atom/branch-misses/ [Kernel PMU event] branch-misses OR cpu_core/branch-misses/ [Kernel PMU event] bus-cycles OR cpu_atom/bus-cycles/ [Kernel PMU event] bus-cycles OR cpu_core/bus-cycles/ [Kernel PMU event] ... The cpu_atom events are still displayed even if atom CPUs are offlined. After: # perf list ... branch-instructions OR cpu_core/branch-instructions/ [Kernel PMU event] branch-misses OR cpu_core/branch-misses/ [Kernel PMU event] bus-cycles OR cpu_core/bus-cycles/ [Kernel PMU event] ... Now only cpu_core events are displayed. Signed-off-by: Jin Yao <yao.jin@linux.intel.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jin Yao <yao.jin@intel.com> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lore.kernel.org/lkml/20210708013701.20347-2-yao.jin@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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 Restructured Text 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.