RPC/XDP overhead

[mouse at mcgill-vision.UUCP]

In article <1567 at PUCC.BITNET>, D0430 at PUCC.BITNET (Paul Lansky) writes:
> When running Vaxen and Suns with NFS what is the cost of a large
> amount (e.g. 2mbyte) of conversion of floats from IEEE->VAX or the
> other way around using xdp?
XDR, it's called; I think it stands for eXternal Data Representation.
> I can see that it would be relatively painless for small amounts of
> data but what happens under larger loads?  Byte-swapping I assume is
> cheap. Does anyone have a quicker solution?

It sounds as though you are afraid NFS will bog things down converting
floats.  Well, it will bog things down, but not because it's converting
floats.  There are very few floats involved in NFS (I can't recall any
off-hand).  If you are using XDR to transfer lots of floats around
yourself, that's your lookout; but it's not NFS's problem.

As I recall, converting between VAX and IEEE floats (or doubles) is
fairly simple for the VAX; a few EXTV/EXTZV and INSV instructions.  I
don't know how time-consuming they are - does a VAX use a barrel
shifter?

					der Mouse

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