Re: OPTIMISTIC_IO

From: Alex Rousskov <rousskov@dont-contact.us>
Date: Sun, 27 Dec 1998 18:08:47 -0700 (MST)

On Sun, 27 Dec 1998, Carlos Maltzahn wrote:

> I noticed the OPTIMISTIC_IO directive - what is the purpose of it? It
> seems to cause less trips through the select loop...

Right. Select()-ing on a file is a NoOp on many (most?) Unixes. In many
environments, selecting for write on a socket usually returns "ready". Thus,
it may be tempting to avoid select() whatsoever for files and "write"
sockets.

The essential code change is simple, and most of the #ifdef-ed lines you see
are there to check for "calling_io_handler" loops and such. With no select()
pause between operations, nasty things may happen if you are not careful.

Alex.

P.S. I am not the author of this experiment and could misinterpret something.
     Cc-ed Duane for verification.
Received on Tue Jul 29 2003 - 13:15:55 MDT

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