Subject: Re: Tweaking NFSv4 to be friendlier to hardware

From: David Robinson <[email-masked]>
Date: Fri, 6 Aug 1999 17:30:07 -0700 (PDT)

> > 2) Add a length field preceding each component operation and component
> > response to allow them to be skipped over
> 
> Yes, for something like a DMA engine it would make it a bit
> easier to scan a compound request looking for juicy chunks
> of DMA-able data.  The downside is that it encumbers every
> compound op with an extra 4 bytes and makes XDR encoding
> more difficult.  Is the extra complexity really worthwhile ?

I find it interesting that you are willing to add an unnecessary
variable length tag but balk at a 4 byte length field.

Complex protocol processors are relatively rare, but there is
significant modern hardware that does checksumming and/or packet
routing based on offsets in packets.  Adding an explicit length
would greatly improve this sort processing as well as allow
concurrent decoding and possibly processing of requests.

	-David

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From: Mike Eisler <[email-masked]>
Date: Sat, 7 Aug 1999 14:47:31 -0700 (PDT)

> variable length tag but balk at a 4 byte length field.

The former is 4 bytes per RPC call, the latter is 4 bytes per 
operation.

I'm agnostic on either issue, but if a length field per operation is
added, operations should be expressed as opaque variable length arrarys the
way RPC authentifcation credentials and verfifiers are.