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Date:      Tue, 24 Jul 2001 17:02:52 -0700 (PDT)
From:      John Baldwin <jhb@FreeBSD.org>
To:        Bala Viswanathan <balaviswanathan@hotmail.com>
Cc:        freebsd-smp@FreeBSD.org
Subject:   RE: SMP performance
Message-ID:  <XFMail.010724170252.jhb@FreeBSD.org>
In-Reply-To: <F172TlKn4ZHkRQq5xVz00005884@hotmail.com>

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On 24-Jul-01 Bala Viswanathan wrote:
> 
> I have been trying to get some idea of the status of SMP support
> in FreeBSD-current especially as far as performance is concerned. I
> have looked at the FreeBSD SMP Project page, other related
> links and the archives of the various FreeBSD mailing lists.
> But have not found any information that appears current.

Right now 95+% (and that's somewhat of a guess, but it should be pretty
close) is still under the Giant lock.  This effectively means interrupts
are blocked out of almost all of the kernel, and is equivalent to running
the entire kernel at splhigh() using spl() semantics.  This should help
explain that the performance is not great right now, nor is it going to
be great until subsystems are locked and moved out of Giant.

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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