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perf tools: Make the mmap length autotuning more robust
If /proc/sys/kernel/perf_event_mlock_kb is not (power of 2 + PAGE_SIZE_in_kb) and we let the perf tools do mmap length autosizing based on that, then, for non-CAP_IPC_LOCK users when /proc/sys/kernel/perf_event_paranoid is > -1, then we get an -EINVAL that ends up in: [acme@ssdandy linux]$ trace usleep 1 Invalid argument [acme@ssdandy linux]$ perf record usleep 1 failed to mmap with 22 (Invalid argument) After this fix: [acme@ssdandy linux]$ trace usleep 1 <SNIP> 0.806 ( 0.006 ms): munmap(addr: 0x7f7e4740a000, len: 66467) = 0 0.869 ( 0.002 ms): brk( ) = 0x7bb000 0.873 ( 0.003 ms): brk(brk: 0x7dc000 ) = 0x7dc000 0.877 ( 0.001 ms): brk( ) = 0x7dc000 0.953 ( 0.058 ms): nanosleep(rqtp: 0x7fff26ab9420 ) = 0 0.959 ( 0.000 ms): exit_group( [acme@ssdandy linux]$ perf record usleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.017 MB perf.data (~759 samples) ] [acme@ssdandy linux]$ Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: David Ahern <dsahern@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/n/tip-6p6l5ou6jev6o7ymc4nn1n2a@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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@ -909,6 +909,8 @@ static size_t perf_evlist__mmap_size(unsigned long pages)
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}
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pages = (max * 1024) / page_size;
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if (!is_power_of_2(pages))
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pages = rounddown_pow_of_two(pages);
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} else if (!is_power_of_2(pages))
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return 0;
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