On Thu, 17 Jun 1999, David S. Miller wrote:
> Please factor in the device number in the buffer cache hash function,
> it matters a lot believe it or not.
taking the minor device number and adding it to the block number would be
simple enough, but mathematically adds very little randomness. i haven't
seen any benchmarks that are improved by keeping the device in the hash
function calculations. can you tell me why you think it should stay?
Attach 32 scsi drives to your machine (perhaps of different sizes),
and scan over the metadata on each of them all at once, observe the
hash table afterwards.
You want as much entropy as you can get from the key.
Later,
David S. Miller
davem@redhat.com
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