Date: Sun, 08 Jun 2008 22:01:57 -0400 From: Chuck Robey <chuckr@telenix.org> To: Brian <bri@brianwhalen.net> Cc: freebsd-questions@freebsd.org Subject: Re: Make buildworld Message-ID: <484C8F15.6050208@telenix.org> In-Reply-To: <484C5D6C.9020401@brianwhalen.net> References: <484BE376.9050301@webrz.net> <484C5D6C.9020401@brianwhalen.net>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Brian wrote: > Jos Chrispijn wrote: >> Can someone tell me the difference between 'make -j2 buildworld' and >> 'make -j4 buildworld' ? >> >> Thanks, >> Jos >> _______________________________________________ >> freebsd-questions@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >> To unsubscribe, send any mail to >> "freebsd-questions-unsubscribe@freebsd.org" > fyi, the below is from /usr/src/UPDATING: > > COMMON ITEMS: > > General Notes > ------------- > Avoid using make -j when upgrading. From time to time in the > past there have been problems using -j with buildworld and/or > installworld. This is especially true when upgrading between > "distant" versions (eg one that cross a major release boundary > or several minor releases, or when several months have passed > on the -current branch). I really don't think that's a fault of make(1), it's a fault of the Makefiles, which have to be written very carefully so that having multiple parallel processes going might screw up building. Yes, it has done that in the past, but it's an occaisonal thing, not a regular thing, because there's a good number of folks who build there kernels with something like -j4. I often do. One just has to be really awake when you hit a problem, or when reporting a build error... rebuild without the -jN. I did some testing, at least for me, I get the most improvements when the number of cores or processors equals the -j number. You can make it higher, even double it, withoout hurting things, but 95% of the improvements come from matching the number of processes to the number of available CPUs (and that' by my own testing, not theory). Still, if you aren't willing to do your won troubleshooting, best to avoid using - -j anything. It's very easy to screw up. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFITI8Uz62J6PPcoOkRAvc0AKCihT7rT4VrDI/6ve1BXfWjXwrsHgCdE4qr F1uwEvIAQt8qNrQADQZbkvI= =g9B0 -----END PGP SIGNATURE-----
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