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Date:      Mon, 12 Feb 2001 16:24:19 -0800
From:      Kent Stewart <kstewart@urx.com>
To:        Matt Dillon <dillon@earth.backplane.com>
Cc:        Dag-Erling Smorgrav <des@ofug.org>, Greg Lehey <grog@lemis.com>, Danny Braniss <danny@cs.huji.ac.il>, freebsd-hackers@FreeBSD.ORG
Subject:   Re: soft updates performance
Message-ID:  <3A887EB3.6BDD7648@urx.com>
References:  <E14RurO-0000Zl-00@cs.huji.ac.il> <xzp7l2wc6v6.fsf@flood.ping.uio.no> <20010213095300.D2178@wantadilla.lemis.com> <xzp3ddjpjlk.fsf@flood.ping.uio.no> <200102122343.f1CNhd053320@earth.backplane.com>

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Matt Dillon wrote:
> 
> :> In fact, it's exactly the opposite.  'make world' is CPU-bound, so the
> :> speed of the I/O system is irrelevant.  If it were I/O bound, soft
> :> updates *would* make a difference, because a number of unnecessary
> :> writes would be eliminated.
> :
> :Read what he writes. Soft updates *did* make a difference - they
> :shaved ~30% off his worldstone. It's parallelization that doesn't make
> :a difference in his case, because his CPU and FSB are fast enough that
> :the I/O system is left completely in the dust. This is a 900 MHz box,
> :probably with a 100 MHz or 133 MHz FSB, not the old 486DX33 you have
> :lying in a corner.
> :
> :DES
> :--
> :Dag-Erling Smorgrav - des@ofug.org
> 
>     A suspect a good chunk of that is not using -pipe.  I would be
>     interested in buildworld numbers with -pipe vs with -pipe + softupdates.
>     Without -pipe softupdates will make a huge difference due to temporary
>     file creation & deletion.
> 
>     When Kirk first tested softupdates against buildworld, he explicitly
>     tested it with and without -pipe and found that much of the performance
>     benefit (for buildworld) occured when not using -pipe.

The times I reported earlier are all with -pipe and are on an AMD
Thunderbird 900, with 256 MB of PC-133 memory, and using 3 - ATA-66
HD's on different controllers. The elapsed time dropped from 58:16 to
45:54 by using softupdates.

Kent

> 
>                                         -Matt
> 
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-- 
Kent Stewart
Richland, WA

mailto:kbstew99@hotmail.com
http://kstewart.urx.com/kstewart/index.html
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