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Date:      Sun, 02 Mar 2003 18:55:21 +0100
From:      "Poul-Henning Kamp" <phk@phk.freebsd.dk>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        "M. Warner Losh" <imp@bsdimp.com>, current@FreeBSD.ORG
Subject:   Re: Any ideas why we can't even boot a i386 ? 
Message-ID:  <9064.1046627721@critter.freebsd.dk>
In-Reply-To: Your message of "Mon, 03 Mar 2003 04:06:41 %2B1100." <20030303034332.Y30986-100000@gamplex.bde.org> 

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In message <20030303034332.Y30986-100000@gamplex.bde.org>, Bruce Evans writes:
>On Sun, 2 Mar 2003, Bruce Evans wrote:
>
>> On Fri, 28 Feb 2003, Poul-Henning Kamp wrote:
>>
>> > My main concern would be if the chips have the necessary "umphf"
>> > to actually do a real-world job once they're done running all the
>> > overhead of 5.0-R.  The lack of cmpxchg8 makes the locking horribly
>> > expensive.
>>
>> Actually, the lack of cmpxchg8 only makes locking more expensive.  It's
>                                                    ^^^^
>
>I.e., strictly more expensive, but not much more.

Bruce, it is not a matter of the relative expensiveness of the various
implementations of locking primitives, its a matter of the cummulative
weight of all the locks we add to the system.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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