Messages in this thread | | | Date | Mon, 26 Sep 2005 00:41:23 -0700 (PDT) | Subject | Re: update_mmu_cache(): fault or not fault ? | From | "David S. Miller" <> |
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org> Date: Mon, 26 Sep 2005 16:22:05 +1000
> The problem is that want to only ever do that kind of hw TLB pre-fill > when update_mmu_cache() is called as the result an actual fault. > However, for some reasons that I'm not 100% sure about (*) > update_mmu_cache() is called from other places, typically in mm/fremap.c > which aren't directly results of faults. > > So I suggest adding an argument to it "int is_fault", that would > basically be '1' on all the call sites in mm/memory.c and '0' in all the > call sites in mm/fremap.c.
You can track this in your port specific code. That's what I do on sparc64 to deal with this case. I record the TLB miss type (D or I tlb), and also whether a write occurred, in a bitmask. Then I check this in update_mmu_cache() to decide whether to prefill.
I store it in current_thread_info() and clear it at the end of fault processing.
Just grep for "FAULT_CODE_*" in the sparc64 code to see how this works.
Although, I'm ambivalent as to whether prefilling helps at all. - 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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