Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!snorkelwacker!usc!sdsu!crash!peterson
From: peterson@crash.cts.com (John Peterson)
Newsgroups: comp.unix.wizards
Subject: Asynchronous I/O under UNIX
Message-ID: <932@crash.cts.com>
Date: 19 Dec 89 07:31:28 GMT
Reply-To: peterson@crash.cts.com (John C. Peterson)
Organization: Crash Time Sharing, El Cajon, CA
Lines: 27
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I am developing a code to LU factor large symmetric matrices on an FPS
522 ( running BSD 4.3 ) which are too large to fit in RAM memory. The
mechanics of "out of core" algorithms are pretty straight forward, but
to be efficient, the I/O should be done asynchronously. There seems to
be no real painless way to do this under UNIX.

   My collegues and I have worked out a rough sketch of a way of doing
asynchronous I/O. One would fork off a copy of your process, the child
would 'nap' until an I/O request came from the parent. Upon receipt of
an I/O request, the child goes off and issues a synchronous I/O request
like one ordinarily does, and then set a flag of some sort when the I/O
has completed. The data to be moved would be stored in memory accessible
to the parent and child processes, probably using System V shared memory.

   Does anyone have a better scheme for doing this? Has any general
implementation of this been posted to any of the other newsgroups?
e-mail responses would be best way to reply.

Thanks in advance, John P.

-- 
+--------------------------------------+
|  John C. Peterson                    |
|  UUCP: { nosc ucsd }!crash!peterson  |
|  ARPA: crash!peterson@nosc.mil       |
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