Date: Fri, 13 Oct 2006 13:47:40 -0700 From: Kent Stewart <kstewart@owt.com> To: freebsd-stable@freebsd.org Subject: Re: FreeBSD and "make -j# buildworld" usability Message-ID: <200610131347.41023.kstewart@owt.com> In-Reply-To: <20061013143130.GW491@dev.null.cz> References: <20061013143130.GW491@dev.null.cz>
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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. I am not interested in system and user time. To me the fastest build is the one that produced the smallest wallclock time or elapsed time, which is the 3rd field in the output of time. The fastest build also yielded the highest cpu utilization, which is the 4th field. I figure specifying a value for -j on single cpu system is simply thrashing the cpu by forcing it to save the environment to work on a different section of the build. I also found that mounting /usr/src and /usr/obj on different controller/HDs from the system reduced the build time. I was using ata-133 HDs and a good scsi would be change the results. It is too easy to test in your environment to see what produces the fastest buildworld. I am going to have to upgrade at some point and an AMD X2 should be interesting. Kent -- Kent Stewart Richland, WA http://www.soyandina.com/ "I am Andean project". http://users.owt.com/kstewart/index.html
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