From owner-svn-src-head@FreeBSD.ORG Mon Jul 8 23:24:05 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 538085DA; Mon, 8 Jul 2013 23:24:05 +0000 (UTC) (envelope-from yaneurabeya@gmail.com) Received: from mail-ve0-x22a.google.com (mail-ve0-x22a.google.com [IPv6:2607:f8b0:400c:c01::22a]) by mx1.freebsd.org (Postfix) with ESMTP id C111B1EC2; Mon, 8 Jul 2013 23:24:04 +0000 (UTC) Received: by mail-ve0-f170.google.com with SMTP id 14so4106974vea.1 for ; Mon, 08 Jul 2013 16:24:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=Mue28M9PuK266fsOgiBvJDC5UFyIhtMdvxesGv6Pskg=; b=KFnd9f+zR7v6CFSyRNTRj35z1szNk1/KnLVFblHnqyB+ALkdIysjXj4MIrGNa/6RF2 wCE9kCz6oS/TxnNWEvxnzZDWsJisDohJ79Dy2bJaKGHcKTtWzmigRhXgcRo9FfEiEtOs wZ6A8JIuM7AaQFF6oNv4i9lUyO/2cRiG+ft754A4f7lefs6SwwSGvqJyyQUxEDE6CIkU XJ77aCCM+kbAu/JWN4x9MMuL+I7oLNAZV2jzuo3p5he6GnTXPBO1D7bfSsAdKtz4KtQJ u45x9PI2o8l80X9bk8FQlye5RUf0LyTyr+Fy9TNRdyHrpdMslD8IC5sV8kpfb9+WH2vN LDMg== MIME-Version: 1.0 X-Received: by 10.52.186.129 with SMTP id fk1mr12459656vdc.66.1373325844249; Mon, 08 Jul 2013 16:24:04 -0700 (PDT) Received: by 10.220.146.145 with HTTP; Mon, 8 Jul 2013 16:24:04 -0700 (PDT) In-Reply-To: <201307081713.51892.jhb@freebsd.org> References: <201307072039.r67KdCdR028908@svn.freebsd.org> <201307081713.51892.jhb@freebsd.org> Date: Mon, 8 Jul 2013 16:24:04 -0700 Message-ID: Subject: Re: svn commit: r253002 - head From: Garrett Cooper To: John Baldwin Content-Type: text/plain; charset=ISO-8859-1 Cc: "svn-src-head@freebsd.org" , "svn-src-all@freebsd.org" , Alfred Perlstein , "src-committers@freebsd.org" X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Jul 2013 23:24:05 -0000 On Mon, Jul 8, 2013 at 2:13 PM, John Baldwin wrote: > On Monday, July 08, 2013 2:23:31 am Garrett Cooper wrote: >> On Sun, Jul 7, 2013 at 7:25 PM, Garrett Cooper > wrote: >> > On Jul 7, 2013, at 2:15 PM, Alfred Perlstein wrote: >> > >> >> On 7/7/13 2:01 PM, Garrett Cooper wrote: >> >>> Why the magic number 12? >> >> >> >> Numbers higher seem to result in worse performance as reported by some > members of my team. >> > >> > The suggestion is good in spirit, but this doesn't justify the reasoning > for this recommendation for all cases. >> > >> > Please revert this change and add a doc page or notes to the dev handbook > discussing what the empirical process and results were for determining this > value so people can come up with their own values that work best with their > hardware and software config. This recommendation is prone to bitrot like some > of the recommendations in tuning(7). >> > >> > Misinformation is sometimes more harmful than no information. >> >> I spoke with Alfred over the phone and did some more careful thought >> about this and I'm rescinding this request. >> >> Alfred did a good job at documenting how JFLAG works (it was >> previously undocumented). My concern over -j12 was performance >> related, and after giving things more careful thought it actually >> makes sense why -j12 was chosen because Westmere and newer processors >> have issues with NUMA and cache locality between multiple processor >> packages as we've seen non-empirically and empirically at Isilon with >> FreeBSD 7 and 10 (it's a known issue that jeffr@ and jhb@ are aware >> of). >> >> I'll come up with a concise patch that does what Alfred was trying to >> achieve and have Alfred review it. >> >> Thanks (and thank you Alfred for the contribution!!!)! > > Westmere is fine, it's post-Westmere that is more troublesome. Even the 6-core Westmeres (I'm being completely dumb here as you and Jeff know a lot more about the NUMA issue than I do as I just caught the tail end of the conversation at BSDCan)? I'm asking because they (iX) are using build.ix as the primary build machine and it has 2 Westmere dies with (IIRC -- please correct me if I'm wrong Alfred/Xin/etc) 6 cores each and are SMT enabled. It also has a boatload of RAM and disks hooked up to an mfi(4) controller (which could be a contributing factor in the performance degradation issue). > I think the comment is not super useful, but don't object enough to want > it to be removed. I always use 'make tinderbox' instead of > 'make universe' though as I want build failures to be obvious. For the > described use case of "checking if kernels build", 'tinderbox' certainly > seems to be the more appropriate target. Changing it from universe to tinderbox seems like a better idea -- I'll put a short note in my proposed patch for that. Thanks! -Garrett