On Sat, 2 Dec 2006, Karsten Weiss wrote: > On Sat, 2 Dec 2006, Christoph Anton Mitterer wrote: > > > I found a severe bug mainly by fortune because it occurs very rarely. > > My test looks like the following: I have about 30GB of testing data on > > This sounds very familiar! One of the Linux compute clusters I > administer at work is a 336 node system consisting of the > following components: > > * 2x Dual-Core AMD Opteron 275 > * Tyan S2891 mainboard > * Hitachi HDS728080PLA380 harddisk > * 4 GB RAM (some nodes have 8 GB) - intensively tested with > memtest86+ > * SUSE 9.3 x86_64 (kernel 2.6.11.4-21.14-smp) - But I've also > e.g. tried the latest openSUSE 10.2 RC1+ kernel 2.6.18.2-33 which > makes no difference. > > We are running LS-Dyna on these machines and discovered a > testcase which shows a similar data corruption. So I can > confirm that the problem is for real an not a hardware defect > of a single machine!
Last week we did some more testing with the following result: We could not reproduce the data corruption anymore if we boot the machines with the kernel parameter "iommu=soft" i.e. if we use software bounce buffering instead of the hw-iommu. (As mentioned before, booting with mem=2g works fine, too, because this disables the iommu altogether.) I.e. on these systems the data corruption only happens if the hw-iommu (PCI-GART) of the Opteron CPUs is in use. Christoph, Erik, Chris: I would appreciate if you would test and hopefully confirm this workaround, too. Best regards, Karsten -- __________________________________________creating IT solutions Dipl.-Inf. Karsten Weiss science + computing ag phone: +49 7071 9457 452 Hagellocher Weg 73 teamline: +49 7071 9457 681 72070 Tuebingen, Germany email: [EMAIL PROTECTED] www.science-computing.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
