[tip:perf/core] perf tools: Fallback to reading sysfs to get cacheline size

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  9a3dc28bb015fc730f7ffc49b7b0abf830b56b61
Gitweb:     http://git.kernel.org/tip/9a3dc28bb015fc730f7ffc49b7b0abf830b56b61
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Tue, 12 Jul 2016 11:01:17 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 12 Jul 2016 15:20:37 -0300

perf tools: Fallback to reading sysfs to get cacheline size

On systems where sysconf(_SC_LEVEL1_DCACHE_LINESIZE) is not available,
such as musl LIBC and Android's bionic libc.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Chris Phlipot <cphlipot0@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-772obxzby758g7m2wmzcejxz@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/perf.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index f7d7dbb..4b2ff02 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -497,6 +497,16 @@ void pthread__unblock_sigwinch(void)
 	pthread_sigmask(SIG_UNBLOCK, &set, NULL);
 }
 
+#ifdef _SC_LEVEL1_DCACHE_LINESIZE
+#define cache_line_size(cacheline_sizep) *cacheline_sizep = sysconf(_SC_LEVEL1_DCACHE_LINESIZE)
+#else
+static void cache_line_size(int *cacheline_sizep)
+{
+	if (sysfs__read_int("devices/system/cpu/cpu0/cache/index0/coherency_line_size", cacheline_sizep))
+		perror("cannot determine cache line size");
+}
+#endif
+
 int main(int argc, const char **argv)
 {
 	const char *cmd;
@@ -509,7 +519,7 @@ int main(int argc, const char **argv)
 
 	/* The page_size is placed in util object. */
 	page_size = sysconf(_SC_PAGE_SIZE);
-	cacheline_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
+	cache_line_size(&cacheline_size);
 
 	if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
 		sysctl_perf_event_max_stack = value;