Date: Thu, 8 Apr 1999 12:36:54 -0700 (PDT) From: Doug White <dwhite@resnet.uoregon.edu> To: Gary Schrock <root@eyelab.psy.msu.edu> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: question about make -jn on single cpu Message-ID: <Pine.BSF.4.03.9904081235320.25113-100000@resnet.uoregon.edu> In-Reply-To: <4.2.0.32.19990408131421.00a9b240@eyelab.msu.edu>
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On Thu, 8 Apr 1999, Gary Schrock wrote: > Is there any advantage to doing a build with make -jn on a single cpu > machine? I did some experimenting with the -current sources over the last > few days (the sources are a couple weeks old, before the egcs stuff), and > I'm finding that it's faster to do it without the -j option than with it: > > make -DNOAOUT buildworld: 58m > make -j2 -DNOAOUT buildworld: 1h 12m > make -j4 -DNOAOUT buildworld: 1h 8m > > Obviously from those results it definitely doesn't appear that there's an > advantage at all. It depends on your system. Obviously it doesn't help you, but on my PPro with an UltraWide 7200RPM SCSI drive it shaves off a bit of time. > This machine is a p2-350, 64M ram, 7200 rpm ide drive, dma not enabled > (I've had problems with dma, so I don't have it enabled right now). Your bottleneck is I/O; increasing -j increases the I/O load on the build, and your system can't take it. Doug White Internet: dwhite@resnet.uoregon.edu | FreeBSD: The Power to Serve http://gladstone.uoregon.edu/~dwhite | www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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