linux-kernel - Re: epoll behaviour after running out of descriptors

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Message-ID: <b2cc26e40811030007w48c3e632v219b72fec1139b40@mail.gmail.com>
Date:	Mon, 3 Nov 2008 09:07:40 +0100
From:	"Olaf van der Spek" <olafvdspek@...il.com>
To:	"Davide Libenzi" <davidel@...ilserver.org>
Cc:	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: epoll behaviour after running out of descriptors

On Sun, Nov 2, 2008 at 11:49 PM, Davide Libenzi <davidel@...ilserver.org> wrote:
> At the time of the first EMFILE, you've filled up the fd space, but not
> the kernel listen backlog. Additions to the backlog, triggers new events,

Shouldn't ET only fire again *after* you drained the queue? When
accept returns EMFILE, you did not drain the queue.

> that you see after the first EMFILE. At a given point, the backlog is
> full, so no new half connections are dropped in there, so no new events
> are generated.

The backlog is 128 entries though, I don't see that many EMFILEs.

> Again, sleeping on (EMFILE && ET) is bad mojo,

It's not always best to free up descriptors right away.

> and nowhere is written that
> events should be generated in the EMFILE->no-EMFILE transitions.

That's true, but I'm saying that this might be handy to have.
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