Messages in this thread | | | Date | Fri, 25 Jan 2008 13:37:13 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 11 of 11] x86: defer cr3 reload when doing pud_clear() |
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Jeremy Fitzhardinge wrote: > PAE mode requires that we reload cr3 in order to guarantee that > changes to the pgd will be noticed by the processor. This means that > in principle pud_clear needs to reload cr3 every time. However, > because reloading cr3 implies a tlb flush, we want to avoid it where > possible.
It only matters (for a processor which supports PGE) if we actually use the namespace in between.
> In huge_pmd_unshare, it is followed by flush_tlb_range, which always > results in a full cr3-reload tlb flush.
This one makes me nervous, as it feels like a side effect of implementation, and not a guarantee by design.
-hpa
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