Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!wuarchive!udel!mmdf
From: wjb%cogsci.COG.JHU.EDU@vm1.nodak.edu
Newsgroups: comp.os.minix
Subject: Re: Better performance for 68K based minix?
Message-ID: <51646@nigel.ee.udel.edu>
Date: 23 Apr 91 17:46:26 GMT
Sender: mmdf@ee.udel.edu
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C.v.W. says:
>This hack is again illegal.
	[refering to my suggestion to allow non buffer cached file IO]

>It is restricted to applications which only do I/O in multiples of
>the disk sector size.
>If you read, e.g. 1 byte from a disk file, you actually read a whole
>block, and this has to be buffered somewhere.

	Oops...  You're right.  You would have to restrict IO in the same
way that IO to the raw disk is restricted.  Hmmm, you would also have to
ignore any excess data in the partial block at the end of the file.  Any
programs that used this "hack" would have to be taught to stat() the file
and only use that many bytes.  Of course, this would cause even more
problems with files that were actively being written too while being read
unbuffered.  Could still be done, but it is becoming less and less
attractive.  Forget I ever mentioned it...

				Bill Bogstad