From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by yocto-www.yoctoproject.org (Postfix) with ESMTP id 6A8E3E00559 for ; Thu, 3 Nov 2011 10:33:53 -0700 (PDT) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP; 03 Nov 2011 10:33:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.67,351,1309762800"; d="scan'208";a="70733187" Received: from amabrams-mobl.amr.corp.intel.com (HELO envy.home) ([10.7.199.147]) by orsmga002.jf.intel.com with ESMTP; 03 Nov 2011 10:33:45 -0700 Message-ID: <4EB2D044.7050207@linux.intel.com> Date: Thu, 03 Nov 2011 10:32:52 -0700 From: Darren Hart User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 MIME-Version: 1.0 To: Gary Thomas References: <4EAD7542.4070204@gna.org> <4EAED7B0.4050909@windriver.com> <4EAEDD3A.9070601@mlbassoc.com> In-Reply-To: <4EAEDD3A.9070601@mlbassoc.com> X-Enigmail-Version: 1.3.2 Cc: yocto@yoctoproject.org Subject: Re: what's the proper value for BB_NUMBER_THREADS? X-BeenThere: yocto@yoctoproject.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Discussion of all things Yocto List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Nov 2011 17:33:53 -0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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