Commit-ID: 800cd25c12981c99e5401c3551ffffd99f1c6c85
Gitweb: http://git.kernel.org/tip/800cd25c12981c99e5401c3551ffffd99f1c6c85
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Thu, 31 Mar 2011 03:35:24 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 31 Mar 2011 13:02:55 +0200
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 <fweisbec@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
LKML-Reference: <1301535324-9735-1-git-send-email-fweisbec@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
tools/perf/builtin-record.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index db6adec..17d1dcb 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) {
--
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