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Re: [Xen-users] xen 3.3 -> tap:aio performance over nfs

To: Stefan de Konink <stefan@xxxxxxxxx>
Subject: Re: [Xen-users] xen 3.3 -> tap:aio performance over nfs
From: C V <rayvittal-lists@xxxxxxxxx>
Date: Mon, 2 Feb 2009 12:23:51 -0800 (PST)
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When you say "increase it", are you referring to the nfs block size (wsize )? 
It is set to 32K. 
The 4k numbers are the actual blocks sent (despite the wsize setting) (I got 
that from from tcpdump)

Your table is a little cryptic, but the closest to my config is I'm guessing is 
the Netapp-NFS-IMG where you get 83M.
or Solaris-NFS-IMG where you get 13M.

----- Original Message ----
From: Stefan de Konink <stefan@xxxxxxxxx>
To: C V <rayvittal-lists@xxxxxxxxx>
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Sent: Friday, January 30, 2009 6:48:27 PM
Subject: Re: [Xen-users] xen 3.3 -> tap:aio performance over nfs

C V wrote:
> It seems that 1. tap:aio causes synchronous writes to the nfs mount (6 
> writes, wait for ack, write 6 more etc) as opposed to NFSv3 async write
> 2. Each synchronous write writes very small blocks (4K bytes vs max of 32K 
> bytes)

Then increase it ;)

> Is there any configuration option to tweak this behavior to get 
> better-performing async writes to the filer?

This is my big comparison table:



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