Messages in this thread |  | | Date | Thu, 08 Nov 2001 23:35:04 -0800 | From | Andrew Morton <> | Subject | Re: speed difference between using hard-linked and modular drives? |
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Ingo Molnar wrote: > > On Thu, 8 Nov 2001, Andrew Morton wrote: > > > Well on my setup, there are more hash buckets than there are pages in > > the system. So - basically empty. If memory serves me, never more > > than two pages in a bucket. > > how much RAM and how many buckets are there on your system? >
urgh. It was ages ago. I shouldn't have stuck my head up ;)
I guess it was 256 megs:
Kernel command line: ... mem=256m Page-cache hash table entries: 65536 (order: 6, 262144 bytes)
And that's one entry per page, yes?
I ended up concluding that
a) The hash is sucky and b) Except for certain specialised workloads, a lookup is usually associated with a big memory copy, so none of it matters and c) given b), the page cache hashtable is on the wrong side of the size/space tradeoff :)
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