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Date:      Sun, 1 Apr 2012 21:04:38 -0400 (EDT)
From:      Rick Macklem <rmacklem@uoguelph.ca>
To:        Sven Brandenburg <sven@crashme.org>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: NFSv3, ZFS, 10GE performance
Message-ID:  <1428634009.2076834.1333328678316.JavaMail.root@erie.cs.uoguelph.ca>
In-Reply-To: <4F746D8C.8010903@crashme.org>

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Sven Brandenburg wrote:
> On 03/26/2012 11:47 PM, Rick Macklem wrote:
> > MAX_BSIZE is 64kb. I'd like to try making that bigger, but haven't
> > gotten
> > around to it yet. (If you wanted to try bumping MAX_BSIZE to 128Kb
> > on both
> > client and server and seeing what happens, that might be
> > interesting, since
> > my understanding is that ZFS uses a 128Kb block size.)
> 
> I finally came around and tested it (with 256k and 1M) - there is good
> and bad news.
> The good news is the system does indeed boot (off of zfs at least, no
> idea on ufs) and it does increase performance.
> I am now seeing roughly 800MB/s off the bat which is quite nice.
> The bad news is that I had to use a Linux client because the FreeBSD
> client declined to work:
> mount_nfs: /mnt, : No buffer space available
> 
> (Although I will freely admit that my knowledge of where to ajdust
> this
> value is rather limited: What I did was changing MAXBSIZE MAXPHYS to
> 1M
> in /usr/src/sys/sys/param.h, remaking world+kernel then reboot.
> I forgot MAXPHYS in my first try and this crashed the client machine
> as
> soon as I tried to mount something via nfs. Notably, the server seems
> to
> be working ok even with a mismatched MAXPHYS/MAXBSIZE).
> 
> So far, the results are very promising.
> 
I did a quick test after rebuilding a kernel with MAXBSIZE set to 131072
and it seemed to work ok. UFS plus NFS. I haven't tried anything larger than
128K. (I don't think you need to change your userland if you are increasing
MAXBSIZE just so NFS can do bigger transfers, but I'm not sure;-)

Btw, I didn't mean to suggest this as something to do for a production system,
but just as a "bleeding edge" experiment, in case you wanted to do so.

I don't see a problem with using 64Kb rsize + a readahead of 8.

Have fun with it, rick
> regards,
> Sven



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