于 2012-2-4 10:16, J. Bruce Fields 写道:
On Sat, Feb 04, 2012 at 12:24:31AM +0800, Mi Jinlong wrote:
于 2012-2-4 4:49, J. Bruce Fields 写道:
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@xxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields<bfields@xxxxxxxxxx>
---
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;
Why don't using target = i.totalram<< (PAGE_SHIFT - 12) as before?
Dividing the calculation into two steps (first convert from pages to
bytes, then divide by 4096) makes it more obvious, and allows me to
stick the comment before the part of the calculation it explains.
So the result seems easier to read.
Yes,
The result of the two forms is more likely different.
The result is the same as long as there's no overflow at the first step
(which would require a machine with an exabyte of ram).
Seem reasonable?
Yes, that is my only concern.
thanks,
Mi Jinlong
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