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Date:      Tue, 19 Jun 2007 23:31:19 +1000
From:      Norberto Meijome <freebsd@meijome.net>
To:        Joe Holden <joe@joeholden.co.uk>
Cc:        "M. Warner Losh" <imp@bsdimp.com>, net@freebsd.org
Subject:   Re: Issue with huge numbers of connections
Message-ID:  <20070619233119.1ff6a8e6@localhost>
In-Reply-To: <46757818.5030005@joeholden.co.uk>
References:  <20070617.114133.778151882.imp@bsdimp.com> <46757818.5030005@joeholden.co.uk>

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On Sun, 17 Jun 2007 19:06:16 +0100
Joe Holden <joe@joeholden.co.uk> wrote:

> kern.ipc.nmbclusters

FWIW, this one in particular ( controls mbuf clusters) will made a huge
difference back in the FBSD 4 days on very heavily used websites. I've had them
tuned up to the order of almost 100K - over that they would lock up on boot -
the lock ups don't seem to happen anymore on 6, but YMMV.
BTW, when the servers I used to run experienced mbuf exhaustion, the machines /
OS would still be operational, but nothing would happen  at the network layer.
A reboot was the only solution I found at the time.

P Jeremy made a v. good point about the timeouts of the close states - bring
everything down to the minimum that makes sense to your app - the defaults are
horribly "kind" to lazy/slow clients :P

Service specific configurations may also affect how your resources are used
(for example, dont use HTTP keep alives as they hog priceless resources). I
know, pretty obvious, but might as well mention it.

B

_________________________
{Beto|Norberto|Numard} Meijome

"But I don't have to know an answer. I don't feel frightened by not knowing
things, by being lost in the mysterious universe without having any purpose,
which is the way it really is, as far as I can tell, possibly. It doesn't
frighten me." Richard Feynman

I speak for myself, not my employer. Contents may be hot. Slippery when wet.
Reading disclaimers makes you go blind. Writing them is worse. You have been
Warned.


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