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Date: Fri, 29 Jul 2011 14:08:44 -0400
From: "J. Bruce Fields" <bfields@fieldses.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>, Neil Brown <neilb@suse.de>,
        David Miller <davem@davemloft.net>, linux-nfs@vger.kernel.org,
        netdev <netdev@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Greg Banks <gnb@fastmail.fm>, bmarson@redhat.com
Subject: Re: [PATCH] sunrpc: use better NUMA affinities
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On Fri, Jul 29, 2011 at 08:02:05PM +0200, Eric Dumazet wrote:
> Le vendredi 29 juillet 2011 à 12:42 -0400, J. Bruce Fields a écrit :
> > On Thu, Jul 28, 2011 at 08:04:09PM +0200, Eric Dumazet wrote:
> > > Use NUMA aware allocations to reduce latencies and increase throughput.
> > > 
> > > sunrpc kthreads can use kthread_create_on_node() if pool_mode is
> > > "percpu" or "pernode", and svc_prepare_thread()/svc_init_buffer() can
> > > also take into account NUMA node affinity for memory allocations.
> > ...
> > > @@ -662,14 +675,16 @@ svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
> > >  		nrservs--;
> > >  		chosen_pool = choose_pool(serv, pool, &state);
> > >  
> > > -		rqstp = svc_prepare_thread(serv, chosen_pool);
> > > +		node = svc_pool_map_get_node(chosen_pool->sp_id);
> > > +		rqstp = svc_prepare_thread(serv, chosen_pool, node);
> > 
> > The only correct value for the third argument there is
> > svc_pool_map_get_node(chosen_pool->sp_id), so let's have
> > svc_prepare_thread() call that itself.
> > 
> 
> I have no idea of what you mean ;)
> 
> I need 'node' for the following kthread_create_on_node()

Doh, of course--apologies.

> > Seems OK otherwise.
> > 
> > Any suggestions on how we should test this?
> 
> I did tests on my machine, seems good.
> 
> I checked that stacks were now correct using :
> "echo t > /proc/sysrq-trigger"

I was wondering more about good tests of nfsd's performance on numa;
that might be more of a question for Greg.

--b.