On 10/31/2011 10:39 AM, Gary Thomas wrote: > On 2011-10-31 11:25, Robert P. J. Day wrote: >> On Mon, 31 Oct 2011, Mark Hatle wrote: >> >>> On 10/30/11 11:15 AM, Robert P. J. Day wrote: >>>> On Sun, 30 Oct 2011, Christian Gagneraud wrote: >>>> >>>>> On 30/10/11 15:32, Robert P. J. Day wrote: >>>>>> >>>>>> all the docs recommend twice the number of cores (AFAICT), yet the >>>>>> template local.conf file suggests that, for a quad core, the value of >>>>>> 4 would be appropriate. shouldn't that say 8? same with >>>>>> PARALLEL_MAKE? >>>>> >>>>> Hi Robert, >>>>> >>>>> The Poky ref manual says (rule of thumb) x2 for BB_NUMBER_THREADS, >>>>> and x1.5 for PARALLEL_MAKE. >>>> >>>> if that's the case, anyone object to my submitting a patch to >>>> update local.conf.sample appropriately? >>>> >>>> rday >>>> >>> >>> I agree the manual and local.conf files should match. The issue >>> seems to be that the perfect values are subjective. Things like >>> memory, disk speed, chipset latency, and of course processor >>> speed/cores all affect the optimal setting. But we do need a >>> consistent rule of thumb.. I myself usually use x2 for both THREADS >>> and MAKE. >> >> that's what i would normally use, assuming that having an overly >> high value for either of those settings can't possibly hurt. if >> that's the consensus, i can adjust the references to say 2x everywhere >> that i know of. just let me know. > > Look back in the archives - I think it was Richard that did a fairly > extensive study of this and he (whoever it was) found that there were > saturation points and trying to get beyond them had a negative impact.
2x on each works well up to about 12 in my experience. Richard has found benefits using 24 on a similar system with more memory. However, if you aren't building on a monster machine, then 2x serves as a reasonable rule of thumb. -- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto