linux-kernel - Re: [patch] export percpu cpuacct cgroup stats

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Date:	Thu, 4 Dec 2008 10:24:54 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Li Zefan <lizf@...fujitsu.com>
Cc:	Ken Chen <kenchen@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [patch] export percpu cpuacct cgroup stats


* Li Zefan <lizf@...fujitsu.com> wrote:

> (I guess it's more appropriate to ask Ingo to pick up this patch)
> 
> Ken Chen wrote:
> > This patch export per-cpu CPU cycle usage for a given cpuacct cgroup.
> > There is a need for a user space monitor daemon to track group CPU
> > usage on per-cpu base.  It is also useful for monitor CFS load
> > balancer behavior by tracking per CPU group usage.
> > 
> > 
> > Signed-off-by: Ken Chen <kenchen@...gle.com>
> > 
> > diff --git a/kernel/sched.c b/kernel/sched.c
> > index b7480fb..cd78948 100644
> > --- a/kernel/sched.c
> > +++ b/kernel/sched.c
> > @@ -9345,12 +9345,34 @@ out:
> >  	return err;
> >  }
> > 
> > +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, "%lld ", percpu);
> 
> Should be %llu. And if we don't cast percpu to unsigned long long, will 
> it trigger compile warning in some archs?

yes.

> > +	}
> > +	seq_printf(m, "\n");
> > +	return 0;
> > +}
> > +
> >  static struct cftype files[] = {
> >  	{
> >  		.name = "usage",
> >  		.read_u64 = cpuusage_read,
> >  		.write_u64 = cpuusage_write,
> >  	},
> > +	{
> > +		.name = "percpu",
> 
> IMO percpu_usage is a better name.

agreed. Looks good otherwise - will wait for v2 of the patch.

	Ingo
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