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Arnaldo Carvalho de Melo
f350ee9549
When the target is a pid, not started by 'perf stat' we need to enable the events, and in that case there is no need to setup affinities as we use a dummy CPU map, with just one entry set to -1. So stop doing it to avoid this needless call to sched_getaffinity(): # strace -ke sched_getaffinity perf stat -e cycles -p 241957 sleep 1 <SNIP> sched_getaffinity(0, 512, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]) = 8 > /usr/lib64/libc-2.33.so(sched_getaffinity@@GLIBC_2.3.4+0x1a) [0xe6eea] > /var/home/acme/bin/perf(affinity__setup+0x6a) [0x5329ca] > /var/home/acme/bin/perf(__evlist__enable.constprop.0+0x23) [0x4b9693] > /var/home/acme/bin/perf(enable_counters+0x14d) [0x42de5d] > /var/home/acme/bin/perf(cmd_stat+0x2358) [0x4310c8] > /var/home/acme/bin/perf(run_builtin+0x6a) [0x4a2cfa] > /var/home/acme/bin/perf(main+0x612) [0x40f8c2] > /usr/lib64/libc-2.33.so(__libc_start_main+0xd4) [0x27b74] > /var/home/acme/bin/perf(_start+0x2d) [0x40fadd] <SNIP> Acked-by: Ian Rogers <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Ian Rogers <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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.