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Message-ID: <3C5DE630.508DE9DB@kegel.com>
Date: Sun, 03 Feb 2002 17:38:56 -0800
From: Dan Kegel <dank@kegel.com>
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To: Aaron Sethman <androsyn@ratbox.org>
CC: Kev <klmitch@MIT.EDU>, Arjen Wolfs <arjen@euro.net>,
        coder-com@undernet.org, feedback@distributopia.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Coder-Com] Re: PROBLEM: high system usage / poor SMPnetwork 
 performance
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Aaron Sethman wrote:
> 
> > 2. you need to wrap your read()/write() calls on the socket with code
> > that notices EWOULDBLOCK
> This is perhaps the part we it disagrees with our code.  I will
> investigate this part.  The way we normally do things is have callbacks
> per fd, that get called when our event occurs doing the read, or, write
> directly.  

That sounds totally fine; in fact, it's how my Poller library works.

> We do check for the EWOULDBLOCK stuff and re-register the
> event.

But do you remember that this fd is ready until EWOULDBLOCK?
i.e. if you're notified that an fd is ready, and then you
don't for whatever reason continue to do I/O on it until EWOULDBLOCK,
you'll never ever be notified that it's ready again.
If your code assumes that it will be notified again anyway,
as with poll(), it will be sorely disappointed.

> The thing we do not currently do is, attempt to read or write
> unless we've received notification first.  This is what I am assuming is
> breaking it.

Yeah, that would break it, too, I think.

- Dan
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