Re: [PATCH 1/2] nfsd: cleanup setting of default max_block_size

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Feb 01, 2012 at 04:46:56PM -0500, bfields wrote:
> On Tue, Jan 31, 2012 at 09:11:48AM +0800, Mi Jinlong wrote:
> >   Should use target = i.totalram << (PAGE_SHIFT - 12);
> > 
> >   target = i.totalram << PAGE_SHIFT; and 
> >   target <<= 12;
> >   means target = i.totalram << (PAGE_SHIFT + 12);
> 
> Yes, thanks for catching that.
> 
> Also, splitting up the calculation as I did above risks overflow at the
> first step.
> 
> I'll fix that....

Here are the fixed patches.--b.

>From 87b0fc7deb5feccf93b022f6a976e8441152dbb2 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Mon, 30 Jan 2012 16:18:35 -0500
Subject: [PATCH 1/2] nfsd: cleanup setting of default max_block_size

Move calculation of the default into a helper function.

Get rid of an unused variable "err" while we're there.

Thanks to Mi Jinlong for catching an arithmetic error in a previous
version.

Cc: Mi Jinlong <mijinlong@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfsd/nfssvc.c |   44 ++++++++++++++++++++++++--------------------
 1 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index eda7d7e..e9eb408 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -307,33 +307,37 @@ static void set_max_drc(void)
 	dprintk("%s nfsd_drc_max_mem %u \n", __func__, nfsd_drc_max_mem);
 }
 
-int nfsd_create_serv(void)
+static int nfsd_get_default_max_blksize(void)
 {
-	int err = 0;
+	struct sysinfo i;
+	unsigned long long target;
+	unsigned long ret;
+
+	si_meminfo(&i);
+	target = i.totalram << PAGE_SHIFT;
+	/*
+	 * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
+	 * machines, but only uses 32K on 128M machines.  Bottom out at
+	 * 8K on 32M and smaller.  Of course, this is only a default.
+	 */
+	target >>= 12;
+
+	ret = NFSSVC_MAXBLKSIZE;
+	while (ret > target && ret >= 8*1024*2)
+		ret /= 2;
+	return ret;
+}
 
+int nfsd_create_serv(void)
+{
 	WARN_ON(!mutex_is_locked(&nfsd_mutex));
 	if (nfsd_serv) {
 		svc_get(nfsd_serv);
 		return 0;
 	}
-	if (nfsd_max_blksize == 0) {
-		/* choose a suitable default */
-		struct sysinfo i;
-		si_meminfo(&i);
-		/* Aim for 1/4096 of memory per thread
-		 * This gives 1MB on 4Gig machines
-		 * But only uses 32K on 128M machines.
-		 * Bottom out at 8K on 32M and smaller.
-		 * Of course, this is only a default.
-		 */
-		nfsd_max_blksize = NFSSVC_MAXBLKSIZE;
-		i.totalram <<= PAGE_SHIFT - 12;
-		while (nfsd_max_blksize > i.totalram &&
-		       nfsd_max_blksize >= 8*1024*2)
-			nfsd_max_blksize /= 2;
-	}
+	if (nfsd_max_blksize == 0)
+		nfsd_max_blksize = nfsd_get_default_max_blksize();
 	nfsd_reset_versions();
-
 	nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
 				      nfsd_last_thread, nfsd, THIS_MODULE);
 	if (nfsd_serv == NULL)
@@ -341,7 +345,7 @@ int nfsd_create_serv(void)
 
 	set_max_drc();
 	do_gettimeofday(&nfssvc_boot);		/* record boot time */
-	return err;
+	return 0;
 }
 
 int nfsd_nrpools(void)
-- 
1.7.5.4


>From 508f92275624fc755104b17945bdc822936f1918 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Mon, 30 Jan 2012 16:21:11 -0500
Subject: [PATCH 2/2] nfsd: fix default iosize calculation on 32bit

The rpc buffers will be allocated out of low memory, so we should really
only be taking that into account.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfsd/nfssvc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index e9eb408..aacf1f4 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -314,7 +314,7 @@ static int nfsd_get_default_max_blksize(void)
 	unsigned long ret;
 
 	si_meminfo(&i);
-	target = i.totalram << PAGE_SHIFT;
+	target = (i.totalram - i.totalhigh) << PAGE_SHIFT;
 	/*
 	 * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
 	 * machines, but only uses 32K on 128M machines.  Bottom out at
-- 
1.7.5.4