Date: 12 Feb 2001 15:29:17 +0100 From: Dag-Erling Smorgrav <des@ofug.org> To: Danny Braniss <danny@cs.huji.ac.il> Cc: Matt Dillon <dillon@earth.backplane.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: soft updates performance Message-ID: <xzp7l2wc6v6.fsf@flood.ping.uio.no> In-Reply-To: Danny Braniss's message of "Sun, 11 Feb 2001 13:40:06 %2B0200" References: <E14RurO-0000Zl-00@cs.huji.ac.il>
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Danny Braniss <danny@cs.huji.ac.il> writes: > i've been doing some experiments with vinum, and doing a make buildworld > (with obj on the same vinum) > without soft-updates ~ 1 hour > with soft-updates ~ 40 minutes > which is a bit better than 3% :-) > > what i can't figure out is why -j 4 didn't make any difference. Because your I/O system is already saturated. The point with -jNN is that one job can run while another is waiting for I/O to complete and vice versa, but as your CPU gets faster the time spent actually compiling etc. becomes insignificant next to the time spent doing I/O, and if you're already doing I/O as fast as you can there's no room for improvement. On a machine with a slower CPU or a faster I/O system, you'd see improvement. DES -- Dag-Erling Smorgrav - des@ofug.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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