diff options
author | Balbir Singh <balbir@linux.vnet.ibm.com> | 2008-09-05 20:12:23 +0400 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-09-05 20:14:35 +0400 |
commit | 49048622eae698e5c4ae61f7e71200f265ccc529 (patch) | |
tree | e568595fe5329e1293eafc3a3cc833dfe89ffbf2 | |
parent | 56c7426b3951e4f35a71d695f1c982989399d6fd (diff) | |
download | linux-49048622eae698e5c4ae61f7e71200f265ccc529.tar.xz |
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>
-rw-r--r-- | fs/proc/array.c | 59 | ||||
-rw-r--r-- | include/linux/sched.h | 4 | ||||
-rw-r--r-- | kernel/exit.c | 6 | ||||
-rw-r--r-- | kernel/sched.c | 59 |
4 files changed, 66 insertions, 62 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, 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) { diff --git a/include/linux/sched.h b/include/linux/sched.h index cfb0d87b99fc..3d9120c5ad15 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1475,6 +1475,10 @@ static inline void put_task_struct(struct task_struct *t) __put_task_struct(t); } +extern cputime_t task_utime(struct task_struct *p); +extern cputime_t task_stime(struct task_struct *p); +extern cputime_t task_gtime(struct task_struct *p); + /* * Per process flags */ diff --git a/kernel/exit.c b/kernel/exit.c index 25ed2ad986df..16395644a98f 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -112,9 +112,9 @@ static void __exit_signal(struct task_struct *tsk) * We won't ever get here for the group leader, since it * will have been the last reference on the signal_struct. */ - sig->utime = cputime_add(sig->utime, tsk->utime); - sig->stime = cputime_add(sig->stime, tsk->stime); - sig->gtime = cputime_add(sig->gtime, tsk->gtime); + sig->utime = cputime_add(sig->utime, task_utime(tsk)); + sig->stime = cputime_add(sig->stime, task_stime(tsk)); + sig->gtime = cputime_add(sig->gtime, task_gtime(tsk)); sig->min_flt += tsk->min_flt; sig->maj_flt += tsk->maj_flt; sig->nvcsw += tsk->nvcsw; diff --git a/kernel/sched.c b/kernel/sched.c index 9a1ddb84e26d..1a5f73c1fcdc 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4179,6 +4179,65 @@ void account_steal_time(struct task_struct *p, cputime_t steal) } /* + * Use precise platform statistics if available: + */ +#ifdef CONFIG_VIRT_CPU_ACCOUNTING +cputime_t task_utime(struct task_struct *p) +{ + return p->utime; +} + +cputime_t task_stime(struct task_struct *p) +{ + return p->stime; +} +#else +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; +} + +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 + +inline cputime_t task_gtime(struct task_struct *p) +{ + return p->gtime; +} + +/* * This function gets called by the timer code, with HZ frequency. * We call it with interrupts disabled. * |