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[Xen-devel] using PageForeign for pte allocation vs. shortcutting __pte_

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] using PageForeign for pte allocation vs. shortcutting __pte_free_tlb()
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Tue, 09 Jan 2007 10:21:39 +0000
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In the course of trying to get CONFIG_HIGHPTE to work I stumbled across this
inconsistency between i386 and x86-64 Linux: i386 uses SetPageForeign() in
(one the non-highpte) case of pte_alloc_one(), and leaves intact native's
definition of __pte_free_tlb(), whereas x86-64 doesn't use the former but
shortcuts the latter to just invoke pte_free(). Obviously it would be nice for
these two to be consistent, the question just is which of the two behaviors
is more desirable: Obviously, performance wise using the PageForeign
mechanism would be preferable, but delta-to-native-wise I would think this
is the less desirable solution.

Thanks for any thoughts or suggestions,
Jan

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