Messages in this thread | | | Date | Thu, 19 Apr 2012 13:20:54 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 3/3] x86, extable: Handle early exceptions |
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On 04/19/2012 01:17 PM, David Daney wrote: > On 04/19/2012 11:55 AM, H. Peter Anvin wrote: >> Either way I suggest picking up David's presorting patchset since it >> is already done and use its infrastructure for any further improvements. > > It does have the advantage of already being implemented. There was a > little feedback on the kbuild portions of the patch. > > If you would like, I will send an updated version of the patch.
Please. It gets us 90% of the way, and we need the infrastructure anyway to do any further work.
>> As far as a linear probe you get an average of n lookups with a >> packing density of 1-1/n so you are right; a linear probe with a >> density of say 1/2 is probably best. >> > > I usually see exception table sizes on the order of 2^10 entries, so I > have to wonder how much you really gain from an O(1) implementation.
Well, for either variant of hash table you end up with ~2 serial memory references as opposed to ~11. No idea if there are workloads where this actually matters.
-hpa
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