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.
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