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On Monday 22 October 2007 14:28, dean gaudet wrote: > On Sun, 21 Oct 2007, Jeremy Fitzhardinge wrote: > > dean gaudet wrote: > > > On Mon, 15 Oct 2007, Nick Piggin wrote: > > >> Yes, as Dave said, vmap (more specifically: vunmap) is very expensive > > >> because it generally has to invalidate TLBs on all CPUs. > > > > > > why is that? ignoring 32-bit archs we have heaps of address space > > > available... couldn't the kernel just burn address space and delay > > > global TLB invalidate by some relatively long time (say 1 second)? > > > > Yes, that's precisely the problem. xfs does delay the unmap, leaving > > stray mappings, which upsets Xen. > > sounds like a bug in xen to me :) You could call it a bug I think. I don't know much about Xen though, whether or not it expects to be able to run an arbitrary OS kernel. Presumably, the hypervisor _could_ write protect and trap writes to *all* page table page mappings. - 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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