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Date:      Sun, 25 Nov 2007 14:41:35 -0600 (CST)
From:      Stephen Montgomery-Smith <stephen@math.missouri.edu>
To:        Robert Watson <rwatson@freebsd.org>
Cc:        binto <binto@triplegate.net.id>, freebsd-hackers@freebsd.org, Girwatson@freebsd.org
Subject:   Re: Before & After Under The Giant Lock
Message-ID:  <20071125143546.V6583@cauchy.math.missouri.edu>
In-Reply-To: <20071125110116.U63238@fledge.watson.org>
References:  <474830F9.90305@zirakzigil.org> <6eb82e0711240638g2cc1e54o1fb1321cafe8ff9f@mail.gmail.com> <1188.202.127.99.4.1195957922.squirrel@webmail.triplegate.net.id> <20071125110116.U63238@fledge.watson.org>

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On Sun, 25 Nov 2007, Robert Watson wrote:

> ........................
> In FreeBSD 8, I expect we'll see a continued focus on both locking 
> granularity and improving opportunities for kernel parallelism by better 
> distributing workloads over CPU pools.  This is important because the number 
> of cores/chip is continuing to increase dramatically, so MP performance is 
> going to be important to keep working on.  That said, the results to date 
> have been extremely promising, and I anticipate that we will continue to find 
> ways to better exploit multiprocessor hardware, especially in the network 
> stack.
>

I just want to add my 2 cents, that my recent experience with FreeBSD MP 
has been extremely positive.  I tend to use highly CPU bound MP programs, 
typically lots and lots of floating point operations.  It used to be that 
Linux beat FreeBSD hands down - now FreeBSD seems to have a slight edge! 
Basically my program runs about twice as fast when I run two threads as 
opposed to one - I cannot see doing any better than that!

(Also when I run 4 threads with 2 cpus, each with hyperthreading, it goes 
2.5 to 3 times faster - surprising since hyperthreading gets quite bad 
press for its performance improvements - I should add that Linux didn't do 
at all well at taking advantage of hyperthreading, running at the same 
speed as with 2 threads.)

Stephen




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