James Clark 3178155d29 perf test brstack: Speed up running test by using tr -s instead of xargs
The brstack test runs quite slowly in software models. Part of the reason
is "xargs -n1" is quite inefficient in replacing spaces with newlines.

While that's not noticeable on normal machines, it is on software models.

Use "tr -s ' ' '\n'" instead which can do the same transformation, but is
much faster. For comparison on an M1 Macbook Pro:

  $ time seq -s ' ' 10000 | xargs -n1 > /dev/null

  real    0m2.729s
  user    0m2.009s
  sys     0m0.914s
  $ time seq -s ' ' 10000 | tr -s ' ' '\n' | grep '.' > /dev/null

  real    0m0.002s
  user    0m0.001s
  sys     0m0.001s

The "grep '.'" is also needed to remove any remaining blank lines.

Signed-off-by: James Clark <james.clark@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241213231312.2640687-2-robh@kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
[robh: Drop changing loop iterations on arm64. Squash blank line fix and redo commit msg]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2025-01-14 14:57:19 -03:00
2024-09-01 20:43:24 -07:00
2022-09-28 09:02:20 +02:00
2024-12-08 14:03:39 -08:00
2024-03-18 03:36:32 -06:00

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.
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