From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pedro Pla Subject: Re: Problem with Gdt driver under smp? Date: Wed, 06 Nov 2002 09:27:53 +0800 Sender: linux-smp-owner@vger.kernel.org Message-ID: <3DC87019.3000504@holidaymarketing.com> References: <3DC0EBB3.9030707@holidaymarketing.com> <20021031120257.GF23217@redhat.com> <3DC71BF8.80100@holidaymarketing.com> <20021105033435.GA16634@redhat.com> <3DC79701.8070802@holidaymarketing.com> <20021105164106.GG16634@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Received: from with PostMaster 3.12.1 (MPR*); Wed, 06 Nov 2002 09:30:07 +800 List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Doug Ledford Cc: linux-scsi@vger.kernel.org, linux-smp@vger.kernel.org Doug Ledford wrote: >On Tue, Nov 05, 2002 at 06:01:37PM +0800, Pedro Pla wrote: > > >>Been running the script all day and still no errors yet, and yes, it >>seems to have used up all the memory or so says a cat /proc/meminfo with >>only a few megs free and no swap activated. This is under a no smp >>compiled kernel, under an smp compiled kernel I think it could die while >>ungzipping the first source directory.. yeah it's that bad, no "subtle" >>problem, just an asap kernel oops or segmentation fault.. can't switch >>to mp 1.1 from mp 1.4 on this motherboard either, or at least I haven't >>found out how yet, it's an intel scb2, intel says nothing about how to >>do so on their sites, and the bios has no such option... at least the >>machine runs flawlessly all tests in non-smp mode which makes me think >>it isn't hardware.. >> >> > >Why would you think that? You don't really think that the linux kernel >SMP support is so flaky that it can't survive the first round of >ungizzipping on an SMP machine do you? I mean, after all, millions of SMP >boxes are out there running the linux kernel every day without a glitch. >If the kernel were that bad, they would *all* be dying. > Of course not :) I have been running linux smp machines for nearly 4 years, since I had to compile the smp support in by putting the smp = 1 manually ;) and it has been a breeze, that's why initially I did think it was definately a hardware issue, however these are "branded" machines and I have tried two different setups with the same kind of peices (identical cpu's, ram, motherboard, raid controller, etc) and both have failed. Yes it could be a fundamental flaw in the design or build of both of these machines, although that is a little out of the ordinary, that is why I suspected it might be some flaw somewhere in the kernel that gave it a hard time running on this particular setup. Or maybe a design flaw in the hardware that makes it not run correctly under linux? However all this hardware is certified to run under Redhat by both the manufacturer intel, and Redhat... > OTOH, several >things on the motherboard change when running SMP mode. Power consumption >goes up (so a bad power supply can cause these problems), you start using >a CPU that isn't being used now (so a totally busted CPU could cause this, >swapping CPU sockets might make it start failing in UP mode as well), >amount of data your are pumping to RAM from CPU goes up (because you have >two CPUs pumping data instead of one, and if the memory controller or >cache coherency controller or RAM itself can't handle the increased speed >of data throughput you get all sorts of errors), etc. There are *tons* of >things that change going from UP to SMP in the hardware and all sorts of >things that used to work fine can start breaking. The fact that your >machine works OK in UP mode means absolutley nothing about how it will >work in SMP mode or whether or not the hardware is up to running SMP. > > > Point taken, I will wait till I receive the other 4 machines with identical configurations, and if each and every one fails under smp mode must I still think it is hardware? that would be 6 seperate machines with identical configurations failing in smp? These are all pure intel except ram and hard disks. Although I did read on the intel site that the raid controller scrmr had problems with the scb2 motherboard, and I did apply the bios upgrade, but it still fails... sigh... maybe I should find a less stressful profession ;) after being on comps for 12 years you wonder just what more can fail when you are pressed for time and bosses are looking over your shoulder ;)