From: Arnaldo Carvalho de Melo <[email protected]> When the user doesn't set --mmap-pages, perf_evlist__mmap() will do it by reading the maximum possible for a non-root user from the /proc/sys/kernel/perf_event_mlock_kb file.
Expose that function so that 'perf trace' can, for root users, to bump mmap-pages to a higher value for root, based on the contents of this proc file. Cc: Adrian Hunter <[email protected]> Cc: David Ahern <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Milian Wolff <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Wang Nan <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- tools/perf/util/evlist.c | 42 +++++++++++++++++++++++++----------------- tools/perf/util/evlist.h | 2 ++ 2 files changed, 27 insertions(+), 17 deletions(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 4c9f510ae18d..6fb5725821de 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -986,26 +986,34 @@ out_unmap: return -1; } -static size_t perf_evlist__mmap_size(unsigned long pages) +unsigned long perf_event_mlock_kb_in_pages(void) { - if (pages == UINT_MAX) { - int max; + unsigned long pages; + 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); - } + 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; + if (!is_power_of_2(pages)) + pages = rounddown_pow_of_two(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 pages; +} + +static size_t perf_evlist__mmap_size(unsigned long pages) +{ + if (pages == UINT_MAX) + pages = perf_event_mlock_kb_in_pages(); + else if (!is_power_of_2(pages)) return 0; return (pages + 1) * page_size; diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index da46423998e8..208897a646ca 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -158,6 +158,8 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str, int unset); +unsigned long perf_event_mlock_kb_in_pages(void); + int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages, bool overwrite, unsigned int auxtrace_pages, bool auxtrace_overwrite); -- 2.5.5
