Date: Mon, 16 Oct 2006 18:33:33 -0400 From: Garance A Drosehn <gad@FreeBSD.org> To: Kent Stewart <kstewart@owt.com>, freebsd-stable@FreeBSD.org Subject: Re: FreeBSD and "make -j# buildworld" usability Message-ID: <p06240813c159b778bb5f@[128.113.24.47]> In-Reply-To: <200610131347.41023.kstewart@owt.com> References: <20061013143130.GW491@dev.null.cz> <200610131347.41023.kstewart@owt.com>
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At 1:47 PM -0700 10/13/06, Kent Stewart wrote: >On Friday 13 October 2006 07:31, Buki wrote: >> Hi, >> >> I searched the archives and web a little but found many different >> opinions on stability/usability of using make -j# with buildworld >> (and buildkernel). >> >> So I am asking if it is a good idea to use make -j on production >> boxes. >> > >I tested buildworlds with different values for -j. On single processors, >using a script that basically looked like > >time make -j? ... > >yielded fastest builds when I didn't specify a value for -j. On dual >cpu's a value around -j8 yielded the fastest build. You might want to repeat those performance tests. The results will change over time, as various system changes are made. I used to see results somewhat similar to yours, but the last time I checked I seemed to get the best results from a dual-cpu system when using -j3 . I believe that change in performance is due to some improvements made to the `make' command itself, which solved some delays that happened when -j was used. However, I do not remember the details. Performance comparisons like this will also depend on all the hardware on the system, and not just the dual-CPU. It can change depending on much memory the machine has, for instance, or how fast the disks are compared to the CPU's. -- Garance Alistair Drosehn = drosehn@rpi.edu Senior Systems Programmer or gad@FreeBSD.org Rensselaer Polytechnic Institute; Troy, NY; USA
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