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    Subject[PATCH v2] 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 not compile with
    'CONFIG_SCHED_DEBUG' option
    2: perf tool should depend on proc file system

    So, this patch call getrusage() to get task's execution time instead
    of reading /proc file

    Reported-by: Török Edwin <edwintorok@gmail.com>
    Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
    ---
    tools/perf/builtin-sched.c | 46 ++++++++++++++-----------------------------
    1 files changed, 15 insertions(+), 31 deletions(-)

    diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
    index 19f43fa..bd57994 100644
    --- a/tools/perf/builtin-sched.c
    +++ b/tools/perf/builtin-sched.c
    @@ -13,7 +13,6 @@
    #include "util/debug.h"
    #include "util/data_map.h"

    -#include <sys/types.h>
    #include <sys/prctl.h>

    #include <semaphore.h>
    @@ -399,49 +398,34 @@ process_sched_event(struct task_desc *this_task __used, struct sched_atom *atom)
    }
    }

    +static u64 get_sum_time(struct rusage *ru)
    +{
    + u64 sum;
    +
    + sum = ru->ru_utime.tv_sec*1e9 + ru->ru_utime.tv_usec*1e3;
    + sum += ru->ru_stime.tv_sec*1e9 + ru->ru_stime.tv_usec*1e3;
    + return sum;
    +}
    +
    static u64 get_cpu_usage_nsec_parent(void)
    {
    struct rusage ru;
    - u64 sum;
    int err;

    err = getrusage(RUSAGE_SELF, &ru);
    BUG_ON(err);

    - sum = ru.ru_utime.tv_sec*1e9 + ru.ru_utime.tv_usec*1e3;
    - sum += ru.ru_stime.tv_sec*1e9 + ru.ru_stime.tv_usec*1e3;
    -
    - return sum;
    + return get_sum_time(&ru);
    }

    static u64 get_cpu_usage_nsec_self(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;
    - int ret;
    -
    - sprintf(filename, "/proc/%d/sched", getpid());
    - file = fopen(filename, "r");
    - BUG_ON(!file);
    -
    - 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);
    + struct rusage ru;
    + int err;

    - return total;
    + err = getrusage(RUSAGE_THREAD, &ru);
    + BUG_ON(err);
    + return get_sum_time(&ru);
    }

    static void *thread_func(void *ctx)
    --
    1.6.1.2
    --
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