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itimers: remove the per-cpu-ish-ness

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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>
This commit is contained in:
Peter Zijlstra
2008-11-24 17:06:57 +01:00
committed by Ingo Molnar
parent ede6f5aea0
commit 490dea45d0
5 changed files with 46 additions and 107 deletions
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kernel/fork.c
+7 -8
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@@ -820,14 +820,15 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
int ret;
if (clone_flags & CLONE_THREAD) {
ret = thread_group_cputime_clone_thread(current);
if (likely(!ret)) {
atomic_inc(&current->signal->count);
atomic_inc(&current->signal->live);
}
return ret;
atomic_inc(&current->signal->count);
atomic_inc(&current->signal->live);
return 0;
}
sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
if (sig)
posix_cpu_timers_init_group(sig);
tsk->signal = sig;
if (!sig)
return -ENOMEM;
@@ -864,8 +865,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
task_unlock(current->group_leader);
posix_cpu_timers_init_group(sig);
acct_init_pacct(&sig->pacct);
tty_audit_fork(sig);