linux-kernel - Re: [PATCH 1/3] epoll: increase default max_user

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Message-ID: <alpine.DEB.1.10.0901280849340.20724@alien.or.mcafeemobile.com>
Date:	Wed, 28 Jan 2009 08:52:51 -0800 (PST)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Vegard Nossum <vegard.nossum@...il.com>
cc:	Bron Gondwana <brong@...tmail.fm>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...e.de>
Subject: Re: [PATCH 1/3] epoll: increase default max_user_instances to 1024

On Wed, 28 Jan 2009, Vegard Nossum wrote:

> On Wed, Jan 28, 2009 at 6:32 AM, Bron Gondwana <brong@...tmail.fm> wrote:
> > That's clearly not happening here - so it seems that maybe our "happy
> > medium" is actually in closer inspection of what's going on rather than
> > a blanket low N to keep N^2 down.
> 
> Mh, could another solution to this all be to limit the number times
> you can add a single epoll descriptor to another descriptor's set?

In the example that was posted, a single fd was added a single time inside 
the other 1000+ fds. Epoll already has detection for too long chains and 
closed loops, but you can't put those in the fast path. And epoll_ctl() is 
one of those.


- Davide


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