aboutsummaryrefslogtreecommitdiffstats
path: root/fs
diff options
context:
space:
mode:
authorBalbir Singh <balbir@linux.vnet.ibm.com>2008-09-05 12:12:23 -0400
committerIngo Molnar <mingo@elte.hu>2008-09-05 12:14:35 -0400
commit49048622eae698e5c4ae61f7e71200f265ccc529 (patch)
treee568595fe5329e1293eafc3a3cc833dfe89ffbf2 /fs
parent56c7426b3951e4f35a71d695f1c982989399d6fd (diff)
sched: fix process time monotonicity
Spencer reported a problem where utime and stime were going negative despite the fixes in commit b27f03d4bdc145a09fb7b0c0e004b29f1ee555fa. The suspected reason for the problem is that signal_struct maintains it's own utime and stime (of exited tasks), these are not updated using the new task_utime() routine, hence sig->utime can go backwards and cause the same problem to occur (sig->utime, adds tsk->utime and not task_utime()). This patch fixes the problem TODO: using max(task->prev_utime, derived utime) works for now, but a more generic solution is to implement cputime_max() and use the cputime_gt() function for comparison. Reported-by: spencer@bluehost.com Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/array.c59
1 files changed, 0 insertions, 59 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 0d6eb33597c6..71c9be59c9c2 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -337,65 +337,6 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
337 return 0; 337 return 0;
338} 338}
339 339
340/*
341 * Use precise platform statistics if available:
342 */
343#ifdef CONFIG_VIRT_CPU_ACCOUNTING
344static cputime_t task_utime(struct task_struct *p)
345{
346 return p->utime;
347}
348
349static cputime_t task_stime(struct task_struct *p)
350{
351 return p->stime;
352}
353#else
354static cputime_t task_utime(struct task_struct *p)
355{
356 clock_t utime = cputime_to_clock_t(p->utime),
357 total = utime + cputime_to_clock_t(p->stime);
358 u64 temp;
359
360 /*
361 * Use CFS's precise accounting:
362 */
363 temp = (u64)nsec_to_clock_t(p->se.sum_exec_runtime);
364
365 if (total) {
366 temp *= utime;
367 do_div(temp, total);
368 }
369 utime = (clock_t)temp;
370
371 p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime));
372 return p->prev_utime;
373}
374
375static cputime_t task_stime(struct task_struct *p)
376{
377 clock_t stime;
378
379 /*
380 * Use CFS's precise accounting. (we subtract utime from
381 * the total, to make sure the total observed by userspace
382 * grows monotonically - apps rely on that):
383 */
384 stime = nsec_to_clock_t(p->se.sum_exec_runtime) -
385 cputime_to_clock_t(task_utime(p));
386
387 if (stime >= 0)
388 p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime));
389
390 return p->prev_stime;
391}
392#endif
393
394static cputime_t task_gtime(struct task_struct *p)
395{
396 return p->gtime;
397}
398
399static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, 340static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
400 struct pid *pid, struct task_struct *task, int whole) 341 struct pid *pid, struct task_struct *task, int whole)
401{ 342{