reported by 'systat iostat' and friends are now much more correct for
RAIDframe devices. Thanks to Andrew Doran for poking me about this,
and for suggestions on and review of the changes.
RAIDframe driver to stop it from eating too much kernel memory when
writing data. But that fix had a nasty side-affect of hurting write
performance (*much* more than I thought it would). These changes nuke
that "fix", and instead put in a more reasonable mechanism for limiting
the number of simultaneous IO's which can be happening for each RAID device.
The result is a noticeable improvement in write throughput. The End.
out-dated comments, and other unneeded stuff. This helps prepare
for cleaning up the rest of the code, and adding new functionality.
No functional changes to the kernel code in this commit.
reads. This avoids a problem where many writes will cause the driver
to allocate way too much memory.
This needs to change to a queueing system later, which will provide a
way to limit the memory consumed by the driver.
Without these changes, raidframe would use 24M or more on my machine when
the buffer cache dumped all its dirty blocks. Now it uses around 200k
or so.
Carnegie Mellon University. Full RAID implementation, including
levels 0, 1, 4, 5, 6, parity logging, and a few other goodies.
Ported to NetBSD by Greg Oster.
