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Date: Mon, 11 Feb 2008 18:36:03 +0100 From: Andi Kleen <ak@...e.de> To: Thomas Gleixner <tglx@...utronix.de> Cc: mingo@...e.hu, linux-kernel@...r.kernel.org Subject: Re: [PATCH] [1/1] CPA: Flush the caches when setting pages not present v2 > This is suboptimal though, as it will trigger a wbinvd() everytime > when we hit a non present pte in a range, whether we did set the entry > in question to not present or not. Do you think that's common? I considered this while writing the code, but figured it was just a oddball case not worth caring about. DEBUG_PAGEALLOC does not call this normally anyways and people should not call this for unallocated mappings anyways. > The gart code unmapping is a special case. This only happens during > boot, so adding a wbinvd() to the gart code is solving this issue > without imposing it on other use cases. > > Another solution for this would be to change the mapping to uncached > before unmapping, so we could avoid the wbinvd() completely. That will work for pci-gart, but not for some future users of set_memory_np() I plan to submit (they run potentially with multiple CPUs online and doing callbacks there would be quite ugly). So I would prefer if you kept some variant of my original patch. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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