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author | Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> | 2009-11-12 05:33:45 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-11-12 15:23:47 +0100 |
commit | 761b1d26df542fd5eb348837351e4d2f3bc7bffe (patch) | |
tree | 3c548070fdf81b618d32f9878b41fb16d26ffcde /kernel/sched.c | |
parent | sched: Make sure task has correct sched_class after policy change (diff) | |
download | linux-761b1d26df542fd5eb348837351e4d2f3bc7bffe.tar.xz linux-761b1d26df542fd5eb348837351e4d2f3bc7bffe.zip |
sched: Fix granularity of task_u/stime()
Originally task_s/utime() were designed to return clock_t but
later changed to return cputime_t by following commit:
commit efe567fc8281661524ffa75477a7c4ca9b466c63
Author: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Thu Aug 23 15:18:02 2007 +0200
It only changed the type of return value, but not the
implementation. As the result the granularity of task_s/utime()
is still that of clock_t, not that of cputime_t.
So using task_s/utime() in __exit_signal() makes values
accumulated to the signal struct to be rounded and coarse
grained.
This patch removes casts to clock_t in task_u/stime(), to keep
granularity of cputime_t over the calculation.
v2:
Use div_u64() to avoid error "undefined reference to `__udivdi3`"
on some 32bit systems.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: xiyou.wangcong@gmail.com
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <4AFB9029.9000208@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r-- | kernel/sched.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 43e61fa04dc7..ab9a034c4a17 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5156,41 +5156,45 @@ cputime_t task_stime(struct task_struct *p) return p->stime; } #else + +#ifndef nsecs_to_cputime +# define nsecs_to_cputime(__nsecs) \ + msecs_to_cputime(div_u64((__nsecs), NSEC_PER_MSEC)) +#endif + cputime_t task_utime(struct task_struct *p) { - clock_t utime = cputime_to_clock_t(p->utime), - total = utime + cputime_to_clock_t(p->stime); + cputime_t utime = p->utime, total = utime + p->stime; u64 temp; /* * Use CFS's precise accounting: */ - temp = (u64)nsec_to_clock_t(p->se.sum_exec_runtime); + temp = (u64)nsecs_to_cputime(p->se.sum_exec_runtime); if (total) { temp *= utime; do_div(temp, total); } - utime = (clock_t)temp; + utime = (cputime_t)temp; - p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime)); + p->prev_utime = max(p->prev_utime, utime); return p->prev_utime; } cputime_t task_stime(struct task_struct *p) { - clock_t stime; + 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 = nsec_to_clock_t(p->se.sum_exec_runtime) - - cputime_to_clock_t(task_utime(p)); + stime = nsecs_to_cputime(p->se.sum_exec_runtime) - task_utime(p); if (stime >= 0) - p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime)); + p->prev_stime = max(p->prev_stime, stime); return p->prev_stime; } |