Messages in this thread | | | Date | Fri, 2 Jan 2004 19:30:26 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [lhcs-devel] Re: in_atomic doesn't count local_irq_disable? |
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On Wed, Dec 31, 2003 at 07:05:53PM +0530, Srivatsa Vaddagiri wrote: > More debugging reveals that the page fault happens > always while doing a prefetch. The prefetch is > present inside list_for_each_entry macros. > > For now I have disabled the x86 prefetch function > to do nothing. > > The test seems to run fine so far w/o any of the > page faults I was experiencing. Will update > at the end of the overnight run if I hit the problem again. > > Wonder if prefetch has some issues on Intel x86 (P3) SMP systems? >
Even after disabling prefetch, I continue to hit page-faults.
With prefetch disabled, it _always_ traps because of trying to dereference a NULL pointer in a list-head. If I break-in into the debugger, the list-head is actually valid (no NULL pointer is present) and hence I don't understand why it read a NULL pointer value in a list head.
With prefetch enabled it traps because of fetch from arbitrary (random) addresses.
So I am no longer sure if this is a prefetch issue or/and a hotplug issue. I'm continuing to investigate and will post any new observation I make here.
FYI, the /proc/cpuinfo output on my SMP system is as below:
processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.730 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1376.25
processor : 1 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.726 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1396.73
processor : 2 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.726 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1396.73
processor : 3 vendor_id : GenuineIntel cpu family : 6 model : 10 model name : Pentium III (Cascades) stepping : 1 cpu MHz : 699.726 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse bogomips : 1396.73
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Thanks and Regards, Srivatsa Vaddagiri, Linux Technology Center, IBM Software Labs, Bangalore, INDIA - 560017 - 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/
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