Messages in this thread Patch in this message | | | Date | Wed, 17 Dec 2014 22:29:15 -0800 | From | tip-bot for Arnaldo Carvalho de Melo <> | Subject | [tip:perf/urgent] perf evlist: Do not use hard coded value for a mmap_pages default |
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Commit-ID: 8185e881f9fd9a2fa01f9d45616f8587f485f2a6 Gitweb: http://git.kernel.org/tip/8185e881f9fd9a2fa01f9d45616f8587f485f2a6 Author: Arnaldo Carvalho de Melo <acme@redhat.com> AuthorDate: Fri, 12 Dec 2014 17:46:45 -0300 Committer: Arnaldo Carvalho de Melo <acme@redhat.com> CommitDate: Tue, 16 Dec 2014 13:38:26 -0300
perf evlist: Do not use hard coded value for a mmap_pages default
So far what is in there by default is what we were using: 512KB + the control page, but the admin may change that, and if it does to a smaller value, all calls to tooling for non root users start failing, requiring that the user manually set --mmap_pages/-m.
Use instead what is in /proc/sys/kernel/perf_event_mlock_kb.
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-2f6mtm8xu3wo5lhkql6jdblh@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- tools/perf/util/evlist.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 7847f38..ac80868 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -893,10 +893,22 @@ out_unmap: static size_t perf_evlist__mmap_size(unsigned long pages) { - /* 512 kiB: default amount of unprivileged mlocked memory */ - if (pages == UINT_MAX) - pages = (512 * 1024) / page_size; - else if (!is_power_of_2(pages)) + if (pages == UINT_MAX) { + int max; + + if (sysctl__read_int("kernel/perf_event_mlock_kb", &max) < 0) { + /* + * Pick a once upon a time good value, i.e. things look + * strange since we can't read a sysctl value, but lets not + * die yet... + */ + max = 512; + } else { + max -= (page_size / 1024); + } + + pages = (max * 1024) / page_size; + } else if (!is_power_of_2(pages)) return 0; return (pages + 1) * page_size;
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