linux-kernel - Re: [PATCH 010 of 11] knfsd: make rpc threads pools numa aware

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Date:	Mon, 07 Aug 2006 21:25:09 +1000
From:	Greg Banks <gnb@...bourne.sgi.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Neil Brown <neilb@...e.de>,
	Linux NFS Mailing List <nfs@...ts.sourceforge.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 010 of 11] knfsd: make rpc threads pools numa aware

On Sun, 2006-08-06 at 19:47, Andrew Morton wrote:
> On Mon, 31 Jul 2006 10:42:34 +1000
> NeilBrown <neilb@...e.de> wrote:
> 
> > knfsd: Actually implement multiple pools.  On NUMA machines, allocate
> > a svc_pool per NUMA node; on SMP a svc_pool per CPU; otherwise a single
> > global pool.  Enqueue sockets on the svc_pool corresponding to the CPU
> > on which the socket bh is run (i.e. the NIC interrupt CPU).  Threads
> > have their cpu mask set to limit them to the CPUs in the svc_pool that
> > owns them.
> > 
> > This is the patch that allows an Altix to scale NFS traffic linearly
> > beyond 4 CPUs and 4 NICs.
> > 
> > Incorporates changes and feedback from Neil Brown, Trond Myklebust,
> > and Christoph Hellwig.
> 
> This makes the NFS client go BUG.  Simple nfsv3 workload (ie: mount, read
> stuff).  Uniproc, FC5.  
> 
> +	BUG_ON(m->mode == SVC_POOL_NONE);
> 

Reproduced on RHAS4; this patch fixes it for me.
--

knfsd: Fix a regression on an NFS client where mounting an
NFS filesystem trips a spurious BUG_ON() in the server code.
Tested using cthon04 lock tests on RHAS4-U2 userspace.

Signed-off-by: Greg Banks <gnb@...bourne.sgi.com>
---

 net/sunrpc/svc.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletion(-)

Index: linux-2.6.18-rc2/net/sunrpc/svc.c
===================================================================
--- linux-2.6.18-rc2.orig/net/sunrpc/svc.c
+++ linux-2.6.18-rc2/net/sunrpc/svc.c
@@ -211,6 +211,11 @@ svc_pool_map_set_cpumask(unsigned int pi
 	struct svc_pool_map *m = &svc_pool_map;
 	unsigned int node; /* or cpu */
 
+	/*
+	 * The caller checks for sv_nrpools > 1, which
+	 * implies that we've been initialized and the
+	 * map mode is not NONE.
+	 */
 	BUG_ON(m->mode == SVC_POOL_NONE);
 
 	switch (m->mode)
@@ -241,7 +246,11 @@ svc_pool_for_cpu(struct svc_serv *serv, 
 	struct svc_pool_map *m = &svc_pool_map;
 	unsigned int pidx = 0;
 
-	BUG_ON(m->mode == SVC_POOL_NONE);
+	/*
+	 * SVC_POOL_NONE happens in a pure client when
+	 * lockd is brought up, so silently treat it the
+	 * same as SVC_POOL_GLOBAL.
+	 */
 
 	switch (m->mode) {
 	case SVC_POOL_PERCPU:





Greg.
-- 
Greg Banks, R&D Software Engineer, SGI Australian Software Group.
I don't speak for SGI.


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