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authorArnaldo Carvalho de Melo <acme@redhat.com>2014-12-12 23:46:45 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2014-12-16 19:38:26 +0300
commit8185e881f9fd9a2fa01f9d45616f8587f485f2a6 (patch)
tree70a7d5dd8ffd2f8b1a360468bcfb7c6cdaad4c0e /tools
parent38d5447d64f367d1f4804ed5c7048d39de4d3311 (diff)
downloadlinux-8185e881f9fd9a2fa01f9d45616f8587f485f2a6.tar.xz
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>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/evlist.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 7847f3885081..ac808680e61c 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;