Date: Tue, 09 Mar 2004 19:29:30 +0100 From: lars <lars@gmx.at> To: Nikolas Britton <freebsd@nbritton.org> Cc: freebsd-newbies@freebsd.org Subject: Re: Update Message-ID: <404E0D0A.7030902@gmx.at> In-Reply-To: <404DF52C.3020008@nbritton.org> References: <200403081055.10903.david.blackorby@comcast.net> <404CDB39.4030504@gmx.at> <404DF52C.3020008@nbritton.org>
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Nikolas Britton wrote: > lars wrote: > >> David Blackorby wrote: >> $cd /usr/src >> $sudo make -j4 buildworld > > > I was told* that running make/buildworld to use mutli processors was a > bad idea, is this still true? > > *Absolute BSD, Book > > I did this on a Intel P4 HTT enabled system...and it's crashing pretty consistently. Albeit not always with the same error, sometimes with a panic: ohci_add_done addr not found ... just now with a Fatal trap 12: page fault while in kernel mode fault code = supervisor read, page not present I'll have to investigate further on that. ----------------------------------------------------------------------------- However when I do above on a P4Mobile (the machine I'm writing on atm), I have no problems. I have this info from http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html Specifically: <quote> It is now possible to specify a -j option to make which will cause it to spawn several simultaneous processes. This is most useful on multi-CPU machines. However, since much of the compiling process is IO bound rather than CPU bound it is also useful on single CPU machines. On a typical single-CPU machine you would run: # make -j4 buildworld make(1) will then have up to 4 processes running at any one time. Empirical evidence posted to the mailing lists shows this generally gives the best performance benefit. If you have a multi-CPU machine and you are using an SMP configured kernel try values between 6 and 10 and see how they speed things up. Be aware that this is still somewhat experimental, and commits to the source tree may occasionally break this feature. If the world fails to compile using this parameter try again without it before you report any problems. </quote> Regards, Lars.
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