From 490dea45d00f01847ebebd007685d564aaf2cd98 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 24 Nov 2008 17:06:57 +0100 Subject: itimers: remove the per-cpu-ish-ness Either we bounce once cacheline per cpu per tick, yielding n^2 bounces or we just bounce a single.. Also, using per-cpu allocations for the thread-groups complicates the per-cpu allocator in that its currently aimed to be a fixed sized allocator and the only possible extention to that would be vmap based, which is seriously constrained on 32 bit archs. So making the per-cpu memory requirement depend on the number of processes is an issue. Lastly, it didn't deal with cpu-hotplug, although admittedly that might be fixable. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- include/linux/sched.h | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 4cae9b81a1f8..c20943eabb4c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -450,6 +450,7 @@ struct task_cputime { cputime_t utime; cputime_t stime; unsigned long long sum_exec_runtime; + spinlock_t lock; }; /* Alternate field names when used to cache expirations. */ #define prof_exp stime @@ -465,7 +466,7 @@ struct task_cputime { * used for thread group CPU clock calculations. */ struct thread_group_cputime { - struct task_cputime *totals; + struct task_cputime totals; }; /* @@ -2180,24 +2181,30 @@ static inline int spin_needbreak(spinlock_t *lock) * Thread group CPU time accounting. */ -extern int thread_group_cputime_alloc(struct task_struct *); -extern void thread_group_cputime(struct task_struct *, struct task_cputime *); - -static inline void thread_group_cputime_init(struct signal_struct *sig) +static inline +void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times) { - sig->cputime.totals = NULL; + struct task_cputime *totals = &tsk->signal->cputime.totals; + unsigned long flags; + + spin_lock_irqsave(&totals->lock, flags); + *times = *totals; + spin_unlock_irqrestore(&totals->lock, flags); } -static inline int thread_group_cputime_clone_thread(struct task_struct *curr) +static inline void thread_group_cputime_init(struct signal_struct *sig) { - if (curr->signal->cputime.totals) - return 0; - return thread_group_cputime_alloc(curr); + sig->cputime.totals = (struct task_cputime){ + .utime = cputime_zero, + .stime = cputime_zero, + .sum_exec_runtime = 0, + }; + + spin_lock_init(&sig->cputime.totals.lock); } static inline void thread_group_cputime_free(struct signal_struct *sig) { - free_percpu(sig->cputime.totals); } /* -- cgit v1.2.1 From baf48f6577e581a9adb8fe849dc80e24b21d171d Mon Sep 17 00:00:00 2001 From: Mandeep Singh Baines Date: Mon, 12 Jan 2009 21:15:17 -0800 Subject: softlock: fix false panic which can occur if softlockup_thresh is reduced At run-time, if softlockup_thresh is changed to a much lower value, touch_timestamp is likely to be much older than the new softlock_thresh. This will cause a false softlockup to be detected. If softlockup_panic is enabled, the system will panic. The fix is to touch all watchdogs before changing softlockup_thresh. Signed-off-by: Mandeep Singh Baines Signed-off-by: Ingo Molnar --- include/linux/sched.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 4cae9b81a1f8..54cbabf3b871 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -293,6 +293,9 @@ extern void sched_show_task(struct task_struct *p); extern void softlockup_tick(void); extern void touch_softlockup_watchdog(void); extern void touch_all_softlockup_watchdogs(void); +extern int proc_dosoftlockup_thresh(struct ctl_table *table, int write, + struct file *filp, void __user *buffer, + size_t *lenp, loff_t *ppos); extern unsigned int softlockup_panic; extern unsigned long sysctl_hung_task_check_count; extern unsigned long sysctl_hung_task_timeout_secs; -- cgit v1.2.1