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.
clean bit. This is somewhat bogus as RAID 0 does not have any parity,
but is a slightly cleaner than other solutions, and makes the handling
of clean bits for RAID 0 consistent with the handling of clean bits at
other RAID levels.
from the tsleep()'s (they probably shouldn't have been there in the
first place!). Making parity re-writing and copybacks interruptable
will require re-designing how a few things are done (e.g. how memory
is freed for structures shipped off to routines that run asynchronously
relative to the calling routine). Fix a few other tsleep's while we're at it.
support a little: clean-bits now also get frobbed on partition
opening/closing, rather than just at device configuration and device
unconfiguration. Schedule shutdownhooks() stuff for nukage at a later
date, since it isn't really necessary any more.
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.
