Messages in this thread | | | Subject | RE: Limit hash table size | Date | Fri, 9 Jan 2004 11:05:12 -0800 | From | "Chen, Kenneth W" <> |
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Anton Blanchard wrote:
>Have you done any analysis of hash depths of large memory machines? We >had some extremely deep pagecache hashchains in 2.4 on a 64GB machine. >While the radix tree should fix that, whos to say we cant get into a >similar situation with the dcache?
We don't have any data to justify any size change for x86, that was the main reason we limit the size by page order.
>Check out how deep some of the inode hash chains are here: >http://www.ussg.iu.edu/hypermail/linux/kernel/0312.0/0105.html
If I read them correctly, most of the distribution is in the first 2 buckets, so it doesn't matter whether you have 100 buckets or 1 million buckets, only first 2 are being hammered hard. So are we wasting memory on the buckets that are not being used?
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