| Subject | Re: [PATCH 4/6] fs: Introduce a per_cpu nr_inodes | From | Peter Zijlstra <> | Date | Thu, 27 Nov 2008 10:32:57 +0100 |
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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@cosmosbay.com> > ---
> @@ -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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