Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 16 Oct 2002 16:34:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 16 Oct 2002 16:34:54 -0400 Received: from adsl-67-114-192-42.dsl.pltn13.pacbell.net ([67.114.192.42]:48951 "EHLO mx1.corp.rackable.com") by vger.kernel.org with ESMTP id ; Wed, 16 Oct 2002 16:34:52 -0400 Message-ID: <3DADD064.8010707@rackable.com> Date: Wed, 16 Oct 2002 13:47:32 -0700 From: Samuel Flory User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.1) Gecko/20020830 X-Accept-Language: en-us, en MIME-Version: 1.0 To: mcuss@cdlsystems.com CC: jamesclv@us.ibm.com, root@chaos.analogic.com, linux-kernel@vger.kernel.org Subject: Re: Kernel reports 4 CPUS instead of 2... References: <200210161228.58897.jamesclv@us.ibm.com> <0d3901c2754c$7bf17060$2c0e10ac@frinkiac7> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 16 Oct 2002 20:40:48.0975 (UTC) FILETIME=[4F688DF0:01C27554] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4148 Lines: 138 Mark Cuss wrote: >Speaking of performance.... :) > >Has anyone done any testing on a dual CPU configuration like this? I've >been testing this box with both the RedHat 8 Stock Kernel (2.4.18.something) >and 2.4.19 from kernel.org. Currently, I can't make the thing perform >anywhere near as fast as my Dual PIII 1 Ghz box (running 2.4.7 for the last >325 days...) . I've been compiling the same block of code on both the >machines and comparing the times. The PIII box is around 7 s, while the new >Xeon Box is 13 or 14s... > >My thinking was that since the CPUs are much faster, and the FSB is faster, >and the disk controller is faster, that the computer would be faster. > >The hardware is obviously faster, I'm sure its just something I've done >wrong in the kernel configuration... If anyone has any advice or words of >wisdom, I'd really appreciate them... > > Try shutting off hyperthreading in the bios. Keep in mind hyperthreading is net loss if you are running a single nonthreaded app. Also you might want to check if there aren't io speed issues. A good way to see the effects positive effects of hyperthreading is a kernel compile. A "make -j 4 bzImage" should be much much faster on the Xeon system with hyperthreading than a P3. > >Mark > >----- Original Message ----- >From: "James Cleverdon" >To: ; "Samuel Flory" >Cc: "Mark Cuss" ; >Sent: Wednesday, October 16, 2002 1:28 PM >Subject: Re: Kernel reports 4 CPUS instead of 2... > > > > >>On Wednesday 16 October 2002 10:54 am, Richard B. Johnson wrote: >> >> >>>On Wed, 16 Oct 2002, Samuel Flory wrote: >>> >>> >>>>>On Wed, 16 Oct 2002, Mark Cuss wrote: >>>>> >>>>>This is the correct behavior. If you don't like this, you can >>>>>swap motherboards with me ;) Otherwise, grin and bear it! >>>>> >>>>> >>>> Wouldn't it be easier just to turn off the hypertreading or jackson >>>>tech option in the bios ;-) >>>> >>>> >>>Why would you ever want to turn it off? You paid for a CPU with >>>two execution units and you want to disable one? This makes >>>no sense unless you are using Windows/2000/Professional, which >>>will trash your disks and all their files if you have two >>>or more CPUs (true). >>> >>> >>No, you're thinking of IBM's Power4 chip, which really does have two CPU >> >> >cores > > >>on one chip, sharing only the L2 cache. >> >>The P4 hyperthreading shares just about all CPU resources between the two >>threads of execution. There are only separate registers, local APIC, and >>some other minor logic for each "CPU" to call its own. All execution >> >> >units > > >>are demand shared between them. (The new "pause" opcode, rep nop, allows >> >> >one > > >>half to yield resources to the other half.) >> >>That's why typical job mixes only get around 20% improvement. Even >> >> >optimized > > >>benchmarks, which run only integer code on one side and floating point on >> >> >the > > >>other only get around a 40% boost. The P4 just doesn't have all that many >>execution units to go around. Future chips will probably do better. >> >> >> >>>Cheers, >>>Dick Johnson >>>Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips). >>>The US military has given us many words, FUBAR, SNAFU, now ENRON. >>>Yes, top management were graduates of West Point and Annapolis. >>> >>> >>-- >>James Cleverdon >>IBM xSeries Linux Solutions >>{jamesclv(Unix, preferred), cleverdj(Notes)} at us dot ibm dot com >> >>- >>To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >>the body of a message to majordomo@vger.kernel.org >>More majordomo info at http://vger.kernel.org/majordomo-info.html >>Please read the FAQ at http://www.tux.org/lkml/ >> >> >> > > > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/