From 49048622eae698e5c4ae61f7e71200f265ccc529 Mon Sep 17 00:00:00 2001 From: Balbir Singh Date: Fri, 5 Sep 2008 18:12:23 +0200 Subject: 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 Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- fs/proc/array.c | 59 --------------------------------------------------------- 1 file changed, 59 deletions(-) (limited to 'fs') 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, return 0; } -/* - * Use precise platform statistics if available: - */ -#ifdef CONFIG_VIRT_CPU_ACCOUNTING -static cputime_t task_utime(struct task_struct *p) -{ - return p->utime; -} - -static cputime_t task_stime(struct task_struct *p) -{ - return p->stime; -} -#else -static 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); - u64 temp; - - /* - * Use CFS's precise accounting: - */ - temp = (u64)nsec_to_clock_t(p->se.sum_exec_runtime); - - if (total) { - temp *= utime; - do_div(temp, total); - } - utime = (clock_t)temp; - - p->prev_utime = max(p->prev_utime, clock_t_to_cputime(utime)); - return p->prev_utime; -} - -static cputime_t task_stime(struct task_struct *p) -{ - clock_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)); - - if (stime >= 0) - p->prev_stime = max(p->prev_stime, clock_t_to_cputime(stime)); - - return p->prev_stime; -} -#endif - -static cputime_t task_gtime(struct task_struct *p) -{ - return p->gtime; -} - static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task, int whole) { -- cgit v1.2.3-59-g8ed1b