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 0 if sysfs attribute is not found (supported) -1 if we failed to read the sysfs attribute Signed-off-by: Jiri Olsa <[email protected]> Cc: Corey Ashford <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Andi Kleen <[email protected]> Cc: David Ahern <[email protected]> --- tools/perf/Makefile | 1 + tools/perf/util/precise.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/util.h | 2 ++ 3 files changed, 48 insertions(+) create mode 100644 tools/perf/util/precise.c diff --git a/tools/perf/Makefile b/tools/perf/Makefile index a84021a..541d242 100644 --- a/tools/perf/Makefile +++ b/tools/perf/Makefile @@ -463,6 +463,7 @@ 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..d801f3e --- /dev/null +++ b/tools/perf/util/precise.c @@ -0,0 +1,45 @@ + +#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: + * 0 if sysfs attribute is not found (supported) + * -1 if we failed to read the sysfs attribute + */ +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 0 if there's no sysfs precise support. */ + precise = 0; + + + return precise; +} diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h index 09b4c26..6d846e9 100644 --- a/tools/perf/util/util.h +++ b/tools/perf/util/util.h @@ -275,4 +275,6 @@ extern unsigned int page_size; struct winsize; void get_term_dimensions(struct winsize *ws); +int perf_precise__get(void); + #endif -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
