From 800cd25c12981c99e5401c3551ffffd99f1c6c85 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 31 Mar 2011 03:35:24 +0200 Subject: [PATCH] perf: mmap 512 kiB by default The default setting of perf record is to mmap 128 pages if the user did not override with -m. However the page size may vary accross different architecture settings, giving different default size between each. Moreover the kernel side still has a default max number of mlocked pages of 512 kiB + 1 page for unprivileged users. 128 + 1 pages with page size > 4096 overlaps this threshold. Thus, better adapt to this limitation and set the default number of pages to fit those 512 kiB + 1 page. Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Cc: Stephane Eranian LKML-Reference: <1301535324-9735-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- tools/perf/builtin-record.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index db6adecf46f1..17d1dcb3c667 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -41,7 +41,7 @@ static u64 user_interval = ULLONG_MAX; static u64 default_interval = 0; static unsigned int page_size; -static unsigned int mmap_pages = 128; +static unsigned int mmap_pages = UINT_MAX; static unsigned int user_freq = UINT_MAX; static int freq = 1000; static int output; @@ -513,6 +513,10 @@ static int __cmd_record(int argc, const char **argv) if (have_tracepoints(&evsel_list->entries)) perf_header__set_feat(&session->header, HEADER_TRACE_INFO); + /* 512 kiB: default amount of unprivileged mlocked memory */ + if (mmap_pages == UINT_MAX) + mmap_pages = (512 * 1024) / page_size; + if (forks) { child_pid = fork(); if (child_pid < 0) {