From: Phy Prabab <phyprabab@yahoo.com>
Subject: Re: Poor NFS performance, kernel 2.6.6.
Date: Fri, 28 May 2004 09:57:25 -0700 (PDT)
Sender: nfs-admin@lists.sourceforge.net
Message-ID: <20040528165725.99256.qmail@web90008.mail.scd.yahoo.com>
References: <20040528135515.GG5657@suse.de>
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Cc: nfs@lists.sourceforge.net, linux-kernel@vger.linux.org
To: Olaf Kirch <okir@suse.de>, Harald Hannelius <harald+nfs@arcada.fi>
In-Reply-To: <20040528135515.GG5657@suse.de>
Errors-To: nfs-admin@lists.sourceforge.net

Hello,

I have been watching this thread with interest.  I
have a 2.6.6-mm5 kernel NFS server in production and
have noticed some significant slow down to that server
(in comparison to an old crusty 2.4.22 kernel and
NetApp).  I too would like to understand the issue
here so I have run iozone as indicated to give another
point of interest.  Note, that during one of the tests
(nfsv2,udp,8192, the server crawled to a halt, load
sky rocketed to 30 with zero load (100% available
reported by top), at this point the server refused
access via ssh/rsh and refused to export any volumes,
but ping-able.  At terminal, everything behavied
normal.

Prior to the lock up, here are the numbers I was
getting:

Client 2.6.6-m5

2.6.6-mm5:

        File size set to 1048576 KB
        Record Size 1024 KB
        SYNC Mode. 
        Command line used:
/var/tmp/iozone/src/current/iozone -s 1g -r 1m -o -i 0
        Output is in Kbytes/sec
        Time Resolution = 0.000001 seconds.
        Processor cache size set to 1024 Kbytes.
        Processor cache line size set to 32 bytes.
        File stride size set to 17 * record size.
                                                      
     
UDP, NFSv2, sync, r/w 8192
         1048576    1024   39889   38745              
                                                      
                      
UDP, NFSv3, sync, r/w 32768
         1048576    1024   12226   10749
TCP, NFSv3, sync, r/w 32768
         1048576    1024   11909   12208              
                                                      
                      
2.4.22
UDP, NFSv3, sync, r/w 32768
         1048576    1024   11259   10761
UDP, NFSv3, sync, r/w 8192
         1048576    1024    6136    6266              
                                                      
        
I cc'ed the linux-kernel mailing list as well.

Cheers,
Phy


--- Olaf Kirch <okir@suse.de> wrote:
> [2.6 over loopback nfs]
> > real    6m21.086s
> > user    0m1.712s
> > sys     0m5.454s
> 
> [2.4 over loopback nfs]
> > real    1m11.875s
> > user    0m1.730s
> > sys     0m7.730s
> 
> This roughly matches some performance issues I've
> been seeing on a 2.6.5
> kernel. Are you using reiser or ext3?
> 
> In general, dd to a local file is much different
> from what NFS does,
> because nfsd flushes data to disk.
> 
> The NFS client will usually issue a COMMIT call
> roughly every 1 Meg,
> so the following should mimic the behavior of nfsd a
> little better,
> when run on your file system locally
> 
> 	iozone -s 1g -r 1m -o -i 0
> 
> Higher numbers indicate better performance.
> 
> Could you run this on 2.4 and 2.6, please?
> 
> Olaf
> -- 
> Olaf Kirch     |  The Hardware Gods hate me.
> okir@suse.de   |
> ---------------+ 
> 
> 
>
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