Messages in this thread | | | Date | Wed, 23 Feb 2011 09:30:22 +0800 | From | Xiao Guangrong <> | Subject | Re: [PATCH 4/7] KVM: sort memslots and use binary search to search the right slot |
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On 02/22/2011 10:25 PM, Avi Kivity wrote: > On 02/22/2011 10:12 AM, Xiao Guangrong wrote: >> Sort memslots then search the slot with binary search to speed up the >> slot searching >> > > I'm not sure if a binary search is the right algorithm here. It introduces a lot of branches which may be mispredicted. > > Options we've discussed are: > > - Sort slots by size, use linear search (so the largest slots are found quickly) > - Weighted balanced tree http://en.wikipedia.org/wiki/Weight-balanced_tree, use weight == slot size >
Yeah, there are the better chooses.
> Both options still make the miss case (mmio) slow. We could cache the result of a miss in an spte by using a reserved bit, and checking the page fault error code (or seeing if we get an ept violation or ept misconfiguration), so if we get repeated mmio on a page, we don't need to search the slot list/tree. >
Sounds good! Will do it, thanks!
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