Re: NFSv4 callback: too many open connections, consider increasing the number of threads.

[NeilBrown <neilb@suse.de>]

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On Mon, 30 Jul 2012 23:16:23 +0000 "Myklebust, Trond"
<Trond.Myklebust@netapp.com> wrote:

> Hi Neil,
> 
> Could you please add the missing s-o-b?
> 
> Cheers
>   Trond

Here 'tis.  Thanks.

NeilBrown

From: NeilBrown <neilb@suse.de>
Date: Tue, 31 Jul 2012 14:33:39 +1000
Subject: [PATCH] nfs: increase number of permitted callback connections.

By default a sunrpc service is limited to (N+3)*20 connections
where N is the number of threads.  This is 80 when N==1.
If this number is exceeded a warning is printed suggesting that
the number of threads be increased.  However with services which
run a single thread, this is impossible.

For such services there is a ->sv_maxconn setting that can be
used to forcibly increase the limit, and silence the message.
This is used by lockd.

The nfs client uses a sunrpc service to handle callbacks and
it too is single-threaded, so to avoid the useless messages,
and to allow a reasonable number of concurrent connections,
we need to set ->sv_maxconn.  1024 seems like a good number.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 23ff18f..9cb1215 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -265,6 +265,10 @@ int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 		ret = -ENOMEM;
 		goto out_err;
 	}
+	/* As there is only one thread we need to over-ride the
+	 * default maximum of 80 connections
+	 */
+	serv->sv_maxconn = 1024;
 
 	ret = svc_bind(serv, net);
 	if (ret < 0) {

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