[RFC][PATCH v2 11/11] perf top: demo of how to use the sysfsinterface

From: Lin Ming
Date: Tue May 18 2010 - 13:50:04 EST


Just a temporary patch to show how to use the pmu sysfs interface...

Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
---
tools/perf/builtin-top.c | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index adc179d..eaa9405 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1206,6 +1206,7 @@ static void start_counter(int i, int counter)
struct perf_event_attr *attr;
int cpu;
int thread_index;
+ int sys_fd;

cpu = profile_cpu;
if (target_tid == -1 && profile_cpu == -1)
@@ -1226,9 +1227,21 @@ static void start_counter(int i, int counter)

for (thread_index = 0; thread_index < thread_num; thread_index++) {
try_again:
+ /*
+ * This is just an ugly demo of how to use the sysfs interface.
+ * You can also parse the <event-name> and open sys file as,
+ * sys_fd = open("/sys/devices/system/cpu/events/<event-name>/event_source/id", O_RDONLY);
+ */
+ sys_fd = open("/sys/devices/system/cpu/event_source/id", O_RDONLY);
+ if (sys_fd != -1)
+ attr->type |= (sys_fd << PERF_EVENT_ATTR_TYPE_BITS) | PERF_EVENT_FD;
+
fd[i][counter][thread_index] = sys_perf_event_open(attr,
all_tids[thread_index], cpu, group_fd, 0);

+ if (sys_fd != -1)
+ close(sys_fd);
+
if (fd[i][counter][thread_index] < 0) {
int err = errno;





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