From 1be300f4cc1ddf975f158b4ab2f880854b29306b Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Tue, 16 Dec 2014 12:19:00 -0300 Subject: [PATCH] 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 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 Cc: Borislav Petkov Cc: David Ahern Cc: Don Zickus Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Mike Galbraith Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/n/tip-6p6l5ou6jev6o7ymc4nn1n2a@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 8eb92cf5d552..7d88327d94a9 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -909,6 +909,8 @@ static size_t perf_evlist__mmap_size(unsigned long pages) } pages = (max * 1024) / page_size; + if (!is_power_of_2(pages)) + pages = rounddown_pow_of_two(pages); } else if (!is_power_of_2(pages)) return 0; -- GitLab