Adding precise util object to get maximum value for
perf_event_attr::precise_ip. The value is exported
via sysfs file '/sys/devices/cpu/precise'.
The interface is:
int perf_precise__get(void)
Returns:
maximum value allowed for perf_event_attr::precise_ip
-1 if we failed to read the sysfs attribute or
sysfs attribute is not found (supported)
Signed-off-by: Jiri Olsa <jo...@redhat.com>
Cc: Corey Ashford <cjash...@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Ingo Molnar <mi...@elte.hu>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Andi Kleen <a...@linux.intel.com>
Cc: David Ahern <dsah...@gmail.com>
Cc: Stephane Eranian <eran...@google.com>
---
tools/perf/Makefile | 1 +
tools/perf/util/precise.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/util.h | 3 +++
3 files changed, 48 insertions(+)
create mode 100644 tools/perf/util/precise.c
diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 55b42b2..477e7bf 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -361,6 +361,7 @@ LIB_OBJS += $(OUTPUT)util/rblist.o
LIB_OBJS += $(OUTPUT)util/intlist.o
LIB_OBJS += $(OUTPUT)util/vdso.o
LIB_OBJS += $(OUTPUT)util/stat.o
+LIB_OBJS += $(OUTPUT)util/precise.o
LIB_OBJS += $(OUTPUT)ui/setup.o
LIB_OBJS += $(OUTPUT)ui/helpline.o
diff --git a/tools/perf/util/precise.c b/tools/perf/util/precise.c
new file mode 100644
index 0000000..70fcba0
--- /dev/null
+++ b/tools/perf/util/precise.c
@@ -0,0 +1,44 @@
+
+#include <linux/kernel.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdio.h>
+#include "sysfs.h"
+#include "util.h"
+
+/*
+ * Returns maximum value allowed for
+ * perf_event_attr::precise_ip, and:
+ * -1 if we failed to read the sysfs attribute or
+ * sysfs attribute is not found (supported)
+ */
+int perf_precise__get(void)
+{
+ static int precise = -1;
+ struct stat st;
+ char path[PATH_MAX];
+
+ if (precise != -1)
+ return precise;
+
+ scnprintf(path, PATH_MAX, "%s/devices/cpu/precise",
+ sysfs_find_mountpoint());
+
+ if (!lstat(path, &st)) {
+ FILE *file;
+
+ file = fopen(path, "r");
+ if (!file)
+ return -1;
+
+ if (1 != fscanf(file, "%d", &precise))
+ pr_debug("failed to read precise info\n");
+
+ fclose(file);
+ } else
+ /* Return -1 if there's no sysfs precise support. */
+ return -1;
+
+ return precise;
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 7a484c9..deeeb54 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -276,4 +276,7 @@ extern unsigned int page_size;
struct winsize;
void get_term_dimensions(struct winsize *ws);
+
+int perf_precise__get(void);
+
#endif /* GIT_COMPAT_UTIL_H */
--
1.7.11.7
--
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