Re: [Patch][RFC] epoll and half closed TCP connections

From: James Antill <james@and.org>
To: "David Schwartz" <davids@webmaster.com>
Cc: "Davide Libenzi" <davidel@xmailserver.org>,
	"Eric Varsanyi" <e0206@foo21.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [Patch][RFC] epoll and half closed TCP connections
Date: 15 Jul 2003 16:27:56 -0400	[thread overview]
Message-ID: <m3y8yz3583.fsf@code.and.org> (raw)
In-Reply-To: <MDEHLPKNGKAHNMBLJOLKGEFKEFAA.davids@webmaster.com>

"David Schwartz" <davids@webmaster.com> writes:

> 	This is really just due to bad coding in 'poll', or more precisely very bad
> for this case. For example, why is it allocating a wait queue buffer if the
> odds that it will need to wait are basically zero? Why is it adding file
> descriptors to the wait queue before it has determined that it needs to
> wait?

 Because this is much easier to do in userspace, it's just not very
well documented that you should almost always call poll() with a zero
timeout first. However it's been there for years, and things have used
it[1].
 There are still optimizations that could have been done to poll() to
speed it up but Linus has generally refused to add them.

[1] http://www.and.org/socket_poll/

-- 
# James Antill -- james@and.org
:0:
* ^From: .*james@and\.org
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