From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.67) (envelope-from ) id 1IGNPJ-0001V5-Pu for garchives@archives.gentoo.org; Wed, 01 Aug 2007 23:15:10 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.14.0/8.14.0) with SMTP id l71NDLMS009824; Wed, 1 Aug 2007 23:13:21 GMT Received: from ciao.gmane.org (main.gmane.org [80.91.229.2]) by robin.gentoo.org (8.14.0/8.14.0) with ESMTP id l71NDLei009816 for ; Wed, 1 Aug 2007 23:13:21 GMT Received: from list by ciao.gmane.org with local (Exim 4.43) id 1IGNNS-0005wo-S2 for gentoo-amd64@lists.gentoo.org; Thu, 02 Aug 2007 01:13:15 +0200 Received: from ip68-230-64-182.ph.ph.cox.net ([68.230.64.182]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 02 Aug 2007 01:13:14 +0200 Received: from 1i5t5.duncan by ip68-230-64-182.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 02 Aug 2007 01:13:14 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: gentoo-amd64@lists.gentoo.org From: Duncan <1i5t5.duncan@cox.net> Subject: [gentoo-amd64] Re: Is there any difference with 4 core? Date: Wed, 1 Aug 2007 23:13:06 +0000 (UTC) Message-ID: References: <46B0A3D5.6080203@singnet.com.sg> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-amd64@gentoo.org Reply-to: gentoo-amd64@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@sea.gmane.org X-Gmane-NNTP-Posting-Host: ip68-230-64-182.ph.ph.cox.net User-Agent: Pan/0.131 (Ghosts: First Variation) Sender: news X-Archives-Salt: f862ecf3-597e-41a6-a317-e6b289b2e295 X-Archives-Hash: 9773c47d8da35846d252e314d4b3224b "P.V.Anthony" posted 46B0A3D5.6080203@singnet.com.sg, excerpted below, on Wed, 01 Aug 2007 23:16:37 +0800: > Now the question is, is it better to go with 2 core or 4 core? > > The reason for this question is, that I heard there is a diminishing > return with more cores. Not sure if this is true with kernel 2.6.21 and > running at 64bit. > > The server needed to built is for the following apps. > > Hardware. > 1. Tyan Tank GT20 (B5191) > 2. 2 x Sata drives > 3. Software raid 1 > 4. 4Gb ram ecc > 5. Intel Core2Duo E6420 or Intel Core2Quad E6600 > > Apps. > 1. Gentoo linux 64bit > 2. Apache 2 > 3. MySql > 4. Postgres > 5. Qmail > 6. Pure-ftpd > 7. Mod_perl > 8. php > 9. ruby > > Will all the instances of the apps be shared among the cores? > > Please share the comments. > > I would really like to save some money. If the 2 core can do the job > there is quite a bit of savings buying just the 2 core. Your application is server, and others have dealt with it. I'll answer for desktop/workstation use, however, since that's what I'm doing here, and other readers may be interested. I've been running a dual socket Opteron for some time now, originally with Opteron 242s. I've upgraded memory to 8 gig (2x2 gig for dual channel off of each CPU/memory-controller, NUMA so each CPU tries to localize memory access to its own 4 gig), and run a 4 spindle kernel RAID (1, 6, 0). /tmp (with /var/tmp a symlink to it) is on tmpfs, so making use of some of that 8 gigs of RAM. RAID-1 /boot, RAID-6 main system, RAID-0 striped for speed swap (4x4GB=16GB swap), ccache, $PORTDIR, and /usr/src. Thus, there's little needing upgrade on the general system. This was my first dual CPU system (before dual-cores came out), and I really appreciate the flexibility it gives me. That said, now that I'm used to it, the dual CPU (single cores) is definitely a bottleneck at times, and I could really use a quad system. That in fact is what I'm planning. I've money set aside for upgrading to dual dual-cores, maxing out the system with Opteron 290s, but at a going price of $1400+ for the pair on pricewatch.com, I'm hoping to wait until Barton comes out and that it will lower the price on the old socket 940 Opterons. I'm hoping it'll drop the pricepoint to about the current one of the 285s, saving me $300-400. I'm definitely looking forward to the upgrade, tho. It's nice to be able to run two CPU hogs, CPU affinity set so each is scheduling on its own CPU, without seriously affecting responsiveness. However, the two CPUs is definitely a limiting factor, now, particularly since other than memory, the rest of the system's all attached to socket 0, so apps such as X run more efficiently on it. By upgrading to dual dual-cores, I'll have two cores able to schedule on that direct-connected socket 0, plus two cores on the less well connected socket 1. Where now I can run X on CPU 0 and my other CPU hogging app on CPU 1, I'm quite looking forward to being able to run both on separate cores on socket 0, while the two cores on socket one could be doing a full emerge -e world for example, without affecting my CPU intensive interactive stuff on the two socket 0 cores /at/ /all/. So yes, I appreciate the dual CPU, but while the popular press is still asking if desktop tasks can scale to dual-core, let alone quad-core, I'm on dual-CPU right now and definitely could use the quad-core or 2 by dual- core system right now! I can't at this point say that I'd be able to make good use of 8 cores, but four, certainly, as two is feeling a bit constrained at this point. As for Intel vs. AMD, with the hypertransport interconnect system AMD has, with AMD's hardware IOMMU for DMA access above the 4 gig boundary (Intel has to emulate it with software bounce-buffers on most of its hardware, kinda nullifying the point of DMA), and with the vaunted Intel performance lead mostly a 32-bit phenomenon, dual dual-core AMD is often more efficient on 64-bit than quad-core Intel. The biggest down side for AMD here is the severe lack of open source support for anything faintly modern, GPU-wise. Unfortunately, Intel's the only real option for anything even half modern in terms of open source driven graphics chipsets. For an x86_64 Linux desktop/ workstation, that more than cancels out the lead AMD would arguably have in multi-core/multi-CPU support, and if I were buying now, it'd be Intel for that reason. AMD simply has to get its act together, and release at least enough specs for its ATI graphics product so the community can build the drivers itself. Or sponsor its own open source drivers. Either way. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- gentoo-amd64@gentoo.org mailing list