Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait

[Ingo Molnar]

On Tue, 6 Feb 2001, Ben LaHaise wrote:

>       - 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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