Commit-ID: 8185e881f9fd9a2fa01f9d45616f8587f485f2a6
Gitweb: http://git.kernel.org/tip/8185e881f9fd9a2fa01f9d45616f8587f485f2a6
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Fri, 12 Dec 2014 17:46:45 -0300
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
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@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-2f6mtm8xu3wo5lhkql6jdblh@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
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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