> - reduce the overhead in submitting block ios, especially for
> large ios. Look at the %CPU usages differences between 512 byte
> blocks and 4KB blocks, this can be better.
my system is already submitting 4KB bhs. If anyone's raw-IO setup submits
512 byte bhs thats a problem of the raw IO code ...
> - make asynchronous io possible in the block layer. This is
> impossible with the current ll_rw_block scheme and io request
> plugging.
why is it impossible?
> You mentioned non-spindle base io devices in your last message. Take
> something like a big RAM disk. Now compare kiobuf base io to buffer
> head based io. Tell me which one is going to perform better.
roughly equal performance when using 4K bhs. And a hell of a lot more
complex and volatile code in the kiobuf case.
Ingo
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