Commit 761b1d26df542fd5eb348837351e4d2f3bc7bffe
Committed by
Ingo Molnar
Ingo Molnar
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ffd44db5f0
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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>
Showing 1 changed file with 13 additions and 9 deletions Side-by-side Diff
kernel/sched.c
| ... | ... | @@ -5156,41 +5156,45 @@ |
| 5156 | 5156 | return p->stime; |
| 5157 | 5157 | } |
| 5158 | 5158 | #else |
| 5159 | + | |
| 5160 | +#ifndef nsecs_to_cputime | |
| 5161 | +# define nsecs_to_cputime(__nsecs) \ | |
| 5162 | + msecs_to_cputime(div_u64((__nsecs), NSEC_PER_MSEC)) | |
| 5163 | +#endif | |
| 5164 | + | |
| 5159 | 5165 | cputime_t task_utime(struct task_struct *p) |
| 5160 | 5166 | { |
| 5161 | - clock_t utime = cputime_to_clock_t(p->utime), | |
| 5162 | - total = utime + cputime_to_clock_t(p->stime); | |
| 5167 | + cputime_t utime = p->utime, total = utime + p->stime; | |
| 5163 | 5168 | u64 temp; |
| 5164 | 5169 | |
| 5165 | 5170 | /* |
| 5166 | 5171 | * Use CFS's precise accounting: |
| 5167 | 5172 | */ |
| 5168 | - temp = (u64)nsec_to_clock_t(p->se.sum_exec_runtime); | |
| 5173 | + temp = (u64)nsecs_to_cputime(p->se.sum_exec_runtime); | |
| 5169 | 5174 | |
| 5170 | 5175 | if (total) { |
| 5171 | 5176 | temp *= utime; |
| 5172 | 5177 | do_div(temp, total); |
| 5173 | 5178 | } |
| 5174 | - utime = (clock_t)temp; | |
| 5179 | + utime = (cputime_t)temp; | |
| 5175 | 5180 | |
| 5176 | - p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime)); | |
| 5181 | + p->prev_utime = max(p->prev_utime, utime); | |
| 5177 | 5182 | return p->prev_utime; |
| 5178 | 5183 | } |
| 5179 | 5184 | |
| 5180 | 5185 | cputime_t task_stime(struct task_struct *p) |
| 5181 | 5186 | { |
| 5182 | - clock_t stime; | |
| 5187 | + cputime_t stime; | |
| 5183 | 5188 | |
| 5184 | 5189 | /* |
| 5185 | 5190 | * Use CFS's precise accounting. (we subtract utime from |
| 5186 | 5191 | * the total, to make sure the total observed by userspace |
| 5187 | 5192 | * grows monotonically - apps rely on that): |
| 5188 | 5193 | */ |
| 5189 | - stime = nsec_to_clock_t(p->se.sum_exec_runtime) - | |
| 5190 | - cputime_to_clock_t(task_utime(p)); | |
| 5194 | + stime = nsecs_to_cputime(p->se.sum_exec_runtime) - task_utime(p); | |
| 5191 | 5195 | |
| 5192 | 5196 | if (stime >= 0) |
| 5193 | - p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime)); | |
| 5197 | + p->prev_stime = max(p->prev_stime, stime); | |
| 5194 | 5198 | |
| 5195 | 5199 | return p->prev_stime; |
| 5196 | 5200 | } |