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perf sched: Fix for getting task's execution time 

In current code, task's execute time is got by reading
'/proc/<pid>/sched' file, it's wrong if the task is created
by pthread_create(), because every thread task has same pid.

This way also has two demerits:

 1: 'perf sched replay' can't work if the kernel is not
    compiled with the 'CONFIG_SCHED_DEBUG' option

 2: perf tool should depend on proc file system

So, this patch uses PERF_COUNT_SW_TASK_CLOCK to get task's
execution time instead of reading /proc file.

Changelog v2 -> v3:
use PERF_COUNT_SW_TASK_CLOCK instead of rusage() as Ingo's
suggestion

Reported-by: Torok Edwin <edwintorok@gmail.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Xiao Guangrong <ericxiao.gr@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <4B1F7322.80103@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
hifive-unleashed-5.1
Xiao Guangrong 2009-12-09 17:51:30 +08:00 committed by Ingo Molnar
parent 822a696111
commit c0c9e72150
1 changed files with 27 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
tools/perf/builtin-sched.c
View File

@ -13,7 +13,6 @@
#include "util/debug.h"
#include "util/data_map.h"
#include <sys/types.h>
#include <sys/prctl.h>
#include <semaphore.h>
@ -414,34 +413,33 @@ static u64 get_cpu_usage_nsec_parent(void)
return sum;
}
static u64 get_cpu_usage_nsec_self(void)
static int self_open_counters(void)
{
char filename [] = "/proc/1234567890/sched";
unsigned long msecs, nsecs;
char *line = NULL;
u64 total = 0;
size_t len = 0;
ssize_t chars;
FILE *file;
struct perf_event_attr attr;
int fd;
memset(&attr, 0, sizeof(attr));
attr.type = PERF_TYPE_SOFTWARE;
attr.config = PERF_COUNT_SW_TASK_CLOCK;
fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
if (fd < 0)
die("Error: sys_perf_event_open() syscall returned"
"with %d (%s)\n", fd, strerror(errno));
return fd;
}
static u64 get_cpu_usage_nsec_self(int fd)
{
u64 runtime;
int ret;
sprintf(filename, "/proc/%d/sched", getpid());
file = fopen(filename, "r");
BUG_ON(!file);
ret = read(fd, &runtime, sizeof(runtime));
BUG_ON(ret != sizeof(runtime));
while ((chars = getline(&line, &len, file)) != -1) {
ret = sscanf(line, "se.sum_exec_runtime : %ld.%06ld\n",
&msecs, &nsecs);
if (ret == 2) {
total = msecs*1e6 + nsecs;
break;
}
}
if (line)
free(line);
fclose(file);
return total;
return runtime;
}
static void *thread_func(void *ctx)
@ -450,9 +448,11 @@ static void *thread_func(void *ctx)
u64 cpu_usage_0, cpu_usage_1;
unsigned long i, ret;
char comm2[22];
int fd;
sprintf(comm2, ":%s", this_task->comm);
prctl(PR_SET_NAME, comm2);
fd = self_open_counters();
again:
ret = sem_post(&this_task->ready_for_work);
@ -462,16 +462,15 @@ again:
ret = pthread_mutex_unlock(&start_work_mutex);
BUG_ON(ret);
cpu_usage_0 = get_cpu_usage_nsec_self();
cpu_usage_0 = get_cpu_usage_nsec_self(fd);
for (i = 0; i < this_task->nr_events; i++) {
this_task->curr_event = i;
process_sched_event(this_task, this_task->atoms[i]);
}
cpu_usage_1 = get_cpu_usage_nsec_self();
cpu_usage_1 = get_cpu_usage_nsec_self(fd);
this_task->cpu_usage = cpu_usage_1 - cpu_usage_0;
ret = sem_post(&this_task->work_done_sem);
BUG_ON(ret);