xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

sched: Introduce task_times() to replace task_{u,s}time() pair

Browse Source 
Functions task_{u,s}time() are called in pair in almost all
cases.  However task_stime() is implemented to call task_utime()
from its inside, so such paired calls run task_utime() twice.

It means we do heavy divisions (div_u64 + do_div) twice to get
utime and stime which can be obtained at same time by one set
of divisions.

This patch introduces a function task_times(*tsk, *utime,
*stime) to retrieve utime and stime at once in better, optimized
way.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
LKML-Reference: <4B0E16AE.906@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Hidetoshi Seto
2009-11-26 14:48:30 +09:00
committed by Ingo Molnar
parent 16bc67edeb
commit d180c5bcce
5 changed files with 44 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
kernel/sched.c
View File

@@ -5191,6 +5191,14 @@ cputime_t task_stime(struct task_struct *p)
{
return p->stime;
}
void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
if (ut)
*ut = task_utime(p);
if (st)
*st = task_stime(p);
}
#else
#ifndef nsecs_to_cputime
@@ -5198,41 +5206,48 @@ cputime_t task_stime(struct task_struct *p)
msecs_to_cputime(div_u64((__nsecs), NSEC_PER_MSEC))
#endif
cputime_t task_utime(struct task_struct *p)
void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
cputime_t utime = p->utime, total = utime + p->stime;
u64 temp;
cputime_t rtime, utime = p->utime, total = utime + p->stime;
/*
* Use CFS's precise accounting:
*/
temp = (u64)nsecs_to_cputime(p->se.sum_exec_runtime);
rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
if (total) {
temp *= utime;
do_div(temp, total);
}
utime = (cputime_t)temp;
u64 temp;
temp = (u64)(rtime * utime);
do_div(temp, total);
utime = (cputime_t)temp;
} else
utime = rtime;
/*
* Compare with previous values, to keep monotonicity:
*/
p->prev_utime = max(p->prev_utime, utime);
return p->prev_utime;
p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);
if (ut)
*ut = p->prev_utime;
if (st)
*st = p->prev_stime;
}
cputime_t task_utime(struct task_struct *p)
{
cputime_t utime;
task_times(p, &utime, NULL);
return utime;
}
cputime_t task_stime(struct task_struct *p)
{
cputime_t stime;
/*
* Use CFS's precise accounting. (we subtract utime from
* the total, to make sure the total observed by userspace
* grows monotonically - apps rely on that):
*/
stime = nsecs_to_cputime(p->se.sum_exec_runtime) - task_utime(p);
if (stime >= 0)
p->prev_stime = max(p->prev_stime, stime);
return p->prev_stime;
task_times(p, NULL, &stime);
return stime;
}
#endif