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Kan Liang 5fa695e7da perf top: Use evsel's cpus to replace user_requested_cpus 
perf top errors out on a hybrid machine
 $perf top

 Error:
 The cycles:P event is not supported.

The perf top expects that the "cycles" is collected on all CPUs in the
system. But for hybrid there is no single "cycles" event which can cover
all CPUs. Perf has to split it into two cycles events, e.g.,
cpu_core/cycles/ and cpu_atom/cycles/. Each event has its own CPU mask.
If a event is opened on the unsupported CPU. The open fails. That's the
reason of the above error out.

Perf should only open the cycles event on the corresponding CPU. The
commit ef91871c96 ("perf evlist: Propagate user CPU maps intersecting
core PMU maps") intersect the requested CPU map with the CPU map of the
PMU. Use the evsel's cpus to replace user_requested_cpus.

The evlist's threads are also propagated to the evsel's threads in
__perf_evlist__propagate_maps(). For a system-wide event, perf appends
a dummy event and assign it to the evsel's threads. For a per-thread
event, the evlist's thread_map is assigned to the evsel's threads. The
same as the other tools, e.g., perf record, using the evsel's threads
when opening an event.

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Hector Martin <marcan@marcan.st>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Closes: https://lore.kernel.org/linux-perf-users/ZXNnDrGKXbEELMXV@kernel.org/
Link: https://lore.kernel.org/r/20231214144612.1092028-1-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
History 2023-12-14 19:09:03 -03:00
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README 

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.