*BSD News Article 88432


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From: cjs@cynic.portal.ca (Curt Sampson)
Newsgroups: comp.os.linux.networking,comp.unix.bsd.bsdi.misc,comp.unix.bsd.misc
Subject: Re: Linux vs BSD
Date: 6 Feb 1997 10:42:33 -0800
Organization: Internet Portal Services, Inc.
Lines: 20
Message-ID: <5dd8mp$la7@cynic.portal.ca>
References: <32DFFEAB.7704@usa.net> <5chl91$bsi@usenet.srv.cis.pitt.edu> <87d8uqu5vt.fsf@localhost.xs4all.nl> <5daqts$1f74@usenet1y.prodigy.net>
NNTP-Posting-Host: cynic.portal.ca
Xref: euryale.cc.adfa.oz.au comp.os.linux.networking:67396 comp.unix.bsd.bsdi.misc:5881 comp.unix.bsd.misc:2276

In article <5daqts$1f74@usenet1y.prodigy.net>,
bill davidsen <davidsen@tmr.com> wrote:
>
>In user or kernel space you should be able to drive the hardware to
>it's limits, and that's what counts.

With NFS in user space you are in the kernel when you receive an
NFS request. You must then leave the kernel to start processing
the request, re-enter the kernel to do the disk I/O, return to
userland to finish processing the request, and re-enter the kernel
again to send the data. These transitions are expensive, and that
is why an in-kernel implementation of NFS is theoretically more
efficient than an equivalant user-land implementation of NFS.

cjs

-- 
Curt Sampson    cjs@portal.ca	   Info at http://www.portal.ca/
Internet Portal Services, Inc.	   Through infinite myst, software reverberates
Vancouver, BC  (604) 257-9400	   In code possess'd of invisible folly.