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Date:      Tue, 3 Apr 2001 23:16:49 -0400
From:      Garrett Rooney <rooneg@electricjellyfish.net>
To:        Bosko Milekic <bmilekic@technokratis.com>
Cc:        Matt Dillon <dillon@earth.backplane.com>, Alfred Perlstein <alfred@FreeBSD.org>, 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:  <20010403231648.B59839@electricjellyfish.net>
In-Reply-To: <20010403194004.A15434@technokratis.com>; from bmilekic@technokratis.com on Tue, Apr 03, 2001 at 07:40:04PM -0400
References:  <200104030315.f333FCX69312@freefall.freebsd.org> <20010403140457.B2952@electricjellyfish.net> <200104031813.f33ID4b58965@earth.backplane.com> <20010403194004.A15434@technokratis.com>

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On Tue, Apr 03, 2001 at 07:40:04PM -0400, Bosko Milekic 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.
> The removal was done nonetheless because it is a step forward toward PCPU
> locks in the mbuf system. The idea is that prior to this removal, what
> was happening is that in the easy uncontended case of allocation, it was
> likely that `ping-ponging' from data cache to data cache would occur a
> maximum of three times per allocation. In that same easy case, with one lock,
> the cache invalidation will happen a maximum of once for what concerns the
> mutex in that same case.

ok, that makes more sense.

[snip more discussion]

> 	In other words, the decision to do this has been planned and
> discussed. :-)

Cool, that's what I figured, but I just wanted to figure out what the plan
was, and this discussion has done that admirably ;-)

i'd just like thank everyone who's been involved in the SMPng work, as it's
been hugely inforamtive to sit on the sidelines and watch, and everyone has
been really willing to answer questions whenever asked.

-- 
garrett rooney                     Unix was not designed to stop you from 
rooneg@electricjellyfish.net       doing stupid things, because that would  
http://electricjellyfish.net/      stop you from doing clever things.

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