Date: Wed, 2 May 2007 18:03:29 -0400 From: Kris Kennaway <kris@obsecurity.org> To: "Mars G. Miro" <marsgmiro@gmail.com> Cc: freebsd-stable@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: mfs and buildworlds on da SunFire x4600 Message-ID: <20070502220329.GA44785@xor.obsecurity.org> In-Reply-To: <28edec3c0705021229w50380f5cqf8608c694bbbf267@mail.gmail.com> References: <28edec3c0705021139h45c785c2s915941c0afb93b5d@mail.gmail.com> <20070502190732.GA42282@xor.obsecurity.org> <28edec3c0705021229w50380f5cqf8608c694bbbf267@mail.gmail.com>
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On Thu, May 03, 2007 at 03:29:05AM +0800, Mars G. Miro wrote:
> >You definitely should be measuring some difference - you need to use
> >time(1) though instead of just estimating.
> >
>
> I did use time, here:
>
> make -j32 buildworld:
> disk
> 3229.975u 8981.269s 18:55.21 1075.6% 3804+2164k 19702+6594io 2158pf+0w
>
> malloc mfs ( mdmfs -SM -o async,noatime -s 2G md {src, obj} )
> 3069.783u 9546.250s 18:57.58 1109.0% 3844+2147k 18504+4422io 2628pf+0w
>
> swap mfs ( mdmfs -S -o async,noatime -s 2G md {src, obj} )
> 3061.682u 9682.776s 19:08.90 1109.2% 3849+2164k 13732+4402io 2053pf+0w
>
> make -j16 buildworld:
> disk
> 3218.722u 7855.885s 17:42.26 1042.5% 3833+2267k 16995+6620io 2445pf+0w
>
> malloc mfs ( mdmfs -SM -o async,noatime -s 2G md {src, obj} )
> 3187.753u 8199.049s 17:57.63 1056.6% 3839+2238k 6890+4436io 2346pf+0w
>
> swap mfs ( mdmfs -S -o async,noatime -s 2G md {src, obj} )
> 3200.400u 8213.312s 18:06.88 1050.1% 3860+2243k 12800+4397io 2303pf+0w
Yeah, looks to me like you're not using your CPUs at 100% capacity
(because buildworld doesn't parallelize well to 16 CPUs), so you're
neither I/O bound nor CPU-bound on average. With a more I/O-bound
test (e.g. maybe just a parallel kernel build) you should see a clear
win from using a md.
Kris
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