Re: [PATCH 4/6] fs: Introduce a per_cpu nr_inodes

[Eric Dumazet]

Peter Zijlstra a écrit :
> On Thu, 2008-11-27 at 00:32 +0100, Eric Dumazet wrote:
> > Avoids cache line ping pongs between cpus and prepare next patch,
> > because updates of nr_inodes metric dont need inode_lock anymore.
> >
> > (socket8 bench result : 25s to 20.5s)
> >
> > Signed-off-by: Eric Dumazet <dada1@xxxxxxxxxxxxx>
> > ---
>
> > @@ -96,9 +96,40 @@ static DEFINE_MUTEX(iprune_mutex);
> >   * Statistics gathering..
> >   */
> >  struct inodes_stat_t inodes_stat;
> > +static DEFINE_PER_CPU(int, nr_inodes);
> >  
> >  static struct kmem_cache * inode_cachep __read_mostly;
> >  
> > +int get_nr_inodes(void)
> > +{
> > +	int cpu;
> > +	int counter = 0;
> > +
> > +	for_each_possible_cpu(cpu)
> > +	    counter += per_cpu(nr_inodes, cpu);
> > +	if (counter < 0)
> > +		counter = 0;
> > +	return counter;
> > +}
>
> It would be good to get a cpu hotplug handler here and move to
> for_each_online_cpu(). People are wanting distro's to be build with
> NR_CPUS=4096.

Hum, I guess we can use regular percpu_counter for this...


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/