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 <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4cae9b8..c20943e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -450,6 +450,7 @@
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 @@
* used for thread group CPU clock calculations.
*/
struct thread_group_cputime {
- struct task_cputime *totals;
+ struct task_cputime totals;
};
/*
@@ -2180,24 +2181,30 @@
* 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(struct task_struct *tsk, struct task_cputime *times)
+{
+ 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 void thread_group_cputime_init(struct signal_struct *sig)
{
- sig->cputime.totals = NULL;
-}
+ sig->cputime.totals = (struct task_cputime){
+ .utime = cputime_zero,
+ .stime = cputime_zero,
+ .sum_exec_runtime = 0,
+ };
-static inline int thread_group_cputime_clone_thread(struct task_struct *curr)
-{
- if (curr->signal->cputime.totals)
- return 0;
- return thread_group_cputime_alloc(curr);
+ spin_lock_init(&sig->cputime.totals.lock);
}
static inline void thread_group_cputime_free(struct signal_struct *sig)
{
- free_percpu(sig->cputime.totals);
}
/*