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Date:      Mon, 01 Oct 2007 11:57:29 +0300
From:      Alexander Motin <mav@FreeBSD.org>
To:        Julian Elischer <julian@elischer.org>
Cc:        freebsd-arch@freebsd.org
Subject:   Re: Kernel thread stack usage
Message-ID:  <4700B679.3070909@FreeBSD.org>
In-Reply-To: <470075EE.1030104@elischer.org>
References:  <46FFD850.1040508@FreeBSD.org> <470075EE.1030104@elischer.org>

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Julian Elischer wrote:
> two mbuf counters. one oncremented whenever there is am mbuf handoff
> that doesn't involve queueing, and is cleared to 0 whenever queueing is
> invoked,
> and one that is continually incremented until the packet leaves the
> machine..
> 
> one to stop packets permanently circulating around a machine and one for
> stack protection..

Using counter in item will not help in case where packet leaves
netgraph, but will come back later. Also item can be destroyed and
recreated by some nodes like ng_ppp.

And even except this counter will not be a best solution as for example
ng_tee node have significantly lower stack usage then previous version
of ng_bpf or tcp stack call from ksocket. ng_tee node can handle a
hundres, while previous ng_bpf would die after 25 calls.

- --
Alexander Motin
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