Re: [patch] export percpu cpuacct cgroup stats

[Ingo Molnar <mingo@elte.hu>]

* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Fri, 5 Dec 2008 10:16:30 -0800 Ken Chen <kenchen@google.com> wrote:
> 
> > +static int cpuacct_percpu_seq_read(struct cgroup *cgroup, struct cftype *cft,
> > +				   struct seq_file *m)
> > +{
> > +	struct cpuacct *ca = cgroup_ca(cgroup);
> > +	u64 percpu;
> > +	int i;
> > +
> > +	for_each_possible_cpu(i) {
> > +		spin_lock_irq(&cpu_rq(i)->lock);
> > +		percpu = *percpu_ptr(ca->cpuusage, i);
> > +		spin_unlock_irq(&cpu_rq(i)->lock);
> > +		seq_printf(m, "%llu ", (unsigned long long) percpu);
> > +	}
> > +	seq_printf(m, "\n");
> > +	return 0;
> > +}
> 
> The locking is only needed for 32-bit, I assume?
> 
> The iteration across all possible CPUs seems a bit lame - that code
> looks pretty easy to convert to hotplug goodness.
> 
> (All of which pertains to existing code, not to this patch).

fair enough. Ken, would you mind updating it in this fashion?

	Ingo