perf tools: Implement counter output multiplexing
Finish the -M/--multiplex option implementation:
- separate it out from group_fd
- correctly set it via the ioctl and dont mmap counters that
are multiplexed
- modify the perf record event loop to deal with buffer-less
counters.
- remove the -g option from perf sched record
- account for unordered events in perf sched latency
- (add -f to perf sched record to ease measurements)
- skip idle threads (pid==0) in latency output
The result is better latency output by 'perf sched latency':
-----------------------------------------------------------------------------------
Task | Runtime ms | Switches | Average delay ms | Maximum delay ms |
-----------------------------------------------------------------------------------
ksoftirqd/8 | 0.071 ms | 2 | avg: 0.458 ms | max: 0.913 ms |
at-spi-registry | 0.609 ms | 19 | avg: 0.013 ms | max: 0.023 ms |
perf | 3.316 ms | 16 | avg: 0.013 ms | max: 0.054 ms |
Xorg | 0.392 ms | 19 | avg: 0.011 ms | max: 0.018 ms |
sleep | 0.537 ms | 2 | avg: 0.009 ms | max: 0.009 ms |
-----------------------------------------------------------------------------------
TOTAL: | 4.925 ms | 58 |
---------------------------------------------
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 79f99db..5f3127e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -49,6 +49,7 @@
static int no_samples = 0;
static int sample_address = 0;
static int multiplex = 0;
+static int multiplex_fd = -1;
static long samples;
static struct timeval last_read;
@@ -471,24 +472,30 @@
*/
if (group && group_fd == -1)
group_fd = fd[nr_cpu][counter];
+ if (multiplex && multiplex_fd == -1)
+ multiplex_fd = fd[nr_cpu][counter];
- event_array[nr_poll].fd = fd[nr_cpu][counter];
- event_array[nr_poll].events = POLLIN;
- nr_poll++;
+ if (multiplex && fd[nr_cpu][counter] != multiplex_fd) {
+ int ret;
- mmap_array[nr_cpu][counter].counter = counter;
- mmap_array[nr_cpu][counter].prev = 0;
- mmap_array[nr_cpu][counter].mask = mmap_pages*page_size - 1;
- mmap_array[nr_cpu][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
- PROT_READ|PROT_WRITE, MAP_SHARED, fd[nr_cpu][counter], 0);
- if (mmap_array[nr_cpu][counter].base == MAP_FAILED) {
- error("failed to mmap with %d (%s)\n", errno, strerror(errno));
- exit(-1);
+ ret = ioctl(fd[nr_cpu][counter], PERF_COUNTER_IOC_SET_OUTPUT, multiplex_fd);
+ assert(ret != -1);
+ } else {
+ event_array[nr_poll].fd = fd[nr_cpu][counter];
+ event_array[nr_poll].events = POLLIN;
+ nr_poll++;
+
+ mmap_array[nr_cpu][counter].counter = counter;
+ mmap_array[nr_cpu][counter].prev = 0;
+ mmap_array[nr_cpu][counter].mask = mmap_pages*page_size - 1;
+ mmap_array[nr_cpu][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
+ PROT_READ|PROT_WRITE, MAP_SHARED, fd[nr_cpu][counter], 0);
+ if (mmap_array[nr_cpu][counter].base == MAP_FAILED) {
+ error("failed to mmap with %d (%s)\n", errno, strerror(errno));
+ exit(-1);
+ }
}
- if (multiplex && fd[nr_cpu][counter] != group_fd)
- ioctl(fd[nr_cpu][counter], PERF_COUNTER_IOC_SET_OUTPUT, group_fd);
-
ioctl(fd[nr_cpu][counter], PERF_COUNTER_IOC_ENABLE);
}
@@ -618,8 +625,10 @@
int hits = samples;
for (i = 0; i < nr_cpu; i++) {
- for (counter = 0; counter < nr_counters; counter++)
- mmap_read(&mmap_array[i][counter]);
+ for (counter = 0; counter < nr_counters; counter++) {
+ if (mmap_array[i][counter].base)
+ mmap_read(&mmap_array[i][counter]);
+ }
}
if (hits == samples) {