*BSD News Article 41937


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From: guy@netapp.com (Guy Harris)
Newsgroups: comp.unix.bsd
Subject: Re: Why select() returns ``exceptional'' for files?
Date: 23 Jan 1995 13:03:39 -0800
Organization: Network Appliance Corporation
Lines: 23
Message-ID: <3g15jb$rs2@nova.netapp.com>
References: <3fois1$5d5@shore.shore.net> <bakulD2ss6p.7M4@netcom.com> <3fuupi$ji8@nova.netapp.com> <bakulD2un2v.JDI@netcom.com>
NNTP-Posting-Host: 192.9.200.13

Bakul Shah <bakul@netcom.com> wrote:
>Polling would not scale too well.  The `right' thing to do (IMHO
>and ideally speaking) is to extend NFS.  On systems running
>earlier versions one would not get the new benefits but so what.

Which benefits?

If you mean the benefits of being able to run applications using selects
on exceptional conditions on files to block until the file changes, I
suspect the effect of that would be that applications wouldn't use
selects on exceptional conditions on files to block until the file
changes, meaning that you wouldn't get those benefits even on *local*
files.  I don't think that counts as a "so what" - i.e., I think you'd
have to implement block-until-change on top of Boring Old NFS V2 Without
The Extra Protocol and Boring Old NFS V3 Without The Extra Protocol,
even if you don't want to do so.

If you mean the performance benefits, yup, they wouldn't get it, but
presumably they'd still be able to run applications that do selects for
exceptional conditions on files.

Of course, "systems running earlier versions" here refers both to client
*and* to server....