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Date:      Tue, 3 Apr 2001 17:35:29 -0700
From:      Alfred Perlstein <alfred@FreeBSD.org>
To:        Matt Dillon <dillon@earth.backplane.com>
Cc:        Bosko Milekic <bmilekic@technokratis.com>, Garrett Rooney <rooneg@electricjellyfish.net>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/sys mbuf.h src/sys/kern uipc_mbuf.c
Message-ID:  <20010403173529.O12164@fw.wintelcom.net>
In-Reply-To: <200104040020.f340Kgi74269@earth.backplane.com>; from dillon@earth.backplane.com on Tue, Apr 03, 2001 at 05:20:42PM -0700
References:  <200104030315.f333FCX69312@freefall.freebsd.org> <20010403140457.B2952@electricjellyfish.net> <200104031813.f33ID4b58965@earth.backplane.com> <20010403194004.A15434@technokratis.com> <200104040020.f340Kgi74269@earth.backplane.com>

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* Matt Dillon <dillon@earth.backplane.com> [010403 17:21] wrote:
> :	The reason for the removal isn't related to pollution of system
> :structures per se (i.e. bloat). There were really only three locks, one
> :for each free list.
> :	The removal is, the way I see it, a slight pessimization in some
> :cases at this moment, due to the increase of contention again, in some cases.
> :...
> 
>     Ok... hmm.  Since compare-exchange support is mandatory now, why not
>     simply use it to implement per-cpu free lists for mbufs that does not
>     require any (mutex) locking at all?  This solves the contention problem
>     and the interrupt problem.

While this is a good idea, it doesn't give us a consistant view of
the stats without additional atomic ops or critical regions.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
Represent yourself, show up at BABUG http://www.babug.org/

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