Al Boldi wrote:
Arjan van de Ven wrote:
Should there be a default scheduler per filesystem? As some
filesystems may perform better/worse with one over another?
It's currently perDevice, and should probably be extended to perMount.
Hi,
Hi!
per mount is going to be "not funny". I assume the situation you are
aiming for is the "3 partitions on a disk, each wants its own elevator".
The way the kernel currently works is that IO requests the filesystem
does are first flattened into an IO for the entire device (eg the
partition mapping is done) and THEN the IO scheduler gets involved to
schedule the IO on a per disk basis.
IC. That probably explains why concurrent io-procs have such a hard time
getting through to the disk. They probably just hang in the flatting phase,
waiting for something to take care of their requests.
flattening is just an addition in the cpu, that's just really boring and shouldn't be visible anywhere
performance wise
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