2006-04-03 01:17:17

by NeilBrown

[permalink] [raw]
Subject: Re: [NFS] [PATCH] knfsd: Correct reserved reply space for read requests.

On Thursday March 30, [email protected] wrote:
> Hi Neil
> Can we use this opportunity to change NFSSVC_MAXBLKSIZE from 32K to 64K to
> match RPCSVC_MAXPAYLOAD. It makes real difference in I/O performance (we
> will still be saving half the space we used to allocate :).
> Thanks, Marc.

Maybe... but why not 128K ??

There is certainly room to increase NFSSVC_MAXBLKSIZE, but I feel that
it needs to be done together with a more detailed look at consequences
in the network layer, particularly TCP window sizes. I wouldn't mind
making a CONFIG_ tunable without that detailed look, but making it a
fixed change I feel less comfortable about.

NeilBrown


2006-04-03 03:28:33

by Marc Eshel

[permalink] [raw]
Subject: Re: [PATCH] knfsd: Correct reserved reply space for read requests.

[email protected] wrote on 04/02/2006 06:17:17 PM:

> On Thursday March 30, [email protected] wrote:
> > Hi Neil
> > Can we use this opportunity to change NFSSVC_MAXBLKSIZE from 32K to
64K to
> > match RPCSVC_MAXPAYLOAD. It makes real difference in I/O performance
(we
> > will still be saving half the space we used to allocate :).
> > Thanks, Marc.
>
> Maybe... but why not 128K ??

Yes, It would be nice to be able to match the Linux client side that can
go to 1MB.

> There is certainly room to increase NFSSVC_MAXBLKSIZE, but I feel that
> it needs to be done together with a more detailed look at consequences
> in the network layer, particularly TCP window sizes. I wouldn't mind
> making a CONFIG_ tunable without that detailed look, but making it a
> fixed change I feel less comfortable about.

Like you said it will need match more work to do it right and also not
waste space for all RPC request to which the maximum possible size is
allocated up front. But until than way not take advantage of this minor
change that can give us significant performance improvement. I run with
NFSSVC_MAXBLKSIZE set to 64K (the only change I made) and saw 10%-15%
improvement for NFS reads. Is there anyone out there that is looking at
making this improvement ?

Marc.

>
> NeilBrown
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by xPML, a groundbreaking scripting
language
> that extends applications into web and mobile media. Attend the live
webcast
> and join the prime developer group breaking into this new coding
territory!
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642
> _______________________________________________
> NFS maillist - [email protected]
> https://lists.sourceforge.net/lists/listinfo/nfs



-------------------------------------------------------
This SF.Net email is sponsored by xPML, a groundbreaking scripting language
that extends applications into web and mobile media. Attend the live webcast
and join the prime developer group breaking into this new coding territory!
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642
_______________________________________________
NFS maillist - [email protected]
https://lists.sourceforge.net/lists/listinfo/nfs