Messages in this thread | | | Date | Sat, 28 Apr 2007 14:28:34 -0700 | From | Andrew Morton <> | Subject | Re: [00/17] Large Blocksize Support V3 |
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On Sat, 28 Apr 2007 12:19:56 -0700 William Lee Irwin III <wli@holomorphy.com> wrote:
> I'm skeptical, however, that the contiguity gains will compensate for > the CPU required to do such with the pcp lists.
It wouldn't surprise me if approximate contiguity is a pretty common case in the pcp lists. Recaim isn't very important here: most pages get freed in truncate and particularly unmap_vmas. If the allocator is handing out pages in reasonably contiguous fashion (and it does, and we're talking about strengthening that) then I'd expect that very often we end up freeing pages which have a lot of locality too. So the sort of tricks which you're discussing might get a pretty good hit rate.
otoh, it's not obvious to me that there's a lot to be gained here. If we repeatedly call the buddy allocator freeing contiguous order-0 pages, all the data structures which are needed to handle those should be in L1 cache and the buddy itself becomes our point-of-collection, if you see what I mean.
Dunno. Profiling should tell? - 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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