has many positive effects including improved smp locking, reducing
interdependencies between mounts that can lead to deadlocks, etc.
- Add the softdep worklist and various counters to the ufsmnt structure.
- Add a mount pointer to the workitem and remove mount pointers from the
various structures derived from the workitem as they are now redundant.
- Remove the poor-man's semaphore protecting softdep_process_worklist and
softdep_flushworklist. Several threads may now process the list
simultaneously.
- Add softdep_waitidle() to block the thread until all pending
dependencies being operated on by other threads have been flushed.
- Use softdep_waitidle() in unmount and snapshots to block either
operation until the fs is stable.
- Remove softdep worklist processing from the syncer and move it into the
softdep_flush() thread. This thread processes all softdep mounts
once each second and when it is called via the new softdep_speedup()
when there is a resource shortage. This removes the softdep hook
from the kernel and various hacks in header files to support it.
Reviewed by/Discussed with: tegge, truckman, mckusick
Tested by: kris
speeds to perform below the desired bitrate and throughput will be erratic.
This makes queueing work on the Geode SC1100, K5 model 0 and IDT WinChip C6
processors.
MFC after: 3 days
with malloc() or contigmalloc() as usual, but try to re-map the allocated
memory into a VA outside the KVA, non-cached, thus making the calls to
bus_dmamap_sync() for these buffers useless.
to call back for completition and something else is holding the taskqueue
waiting for ATA to return data.
This should clear up the "semaphore timeout !! DANGER Will Robinson !!"
in most situations, and log "taskqueue timeout - completing request directly"
instead, with a delayed "WARNING - freeing taskqueue zombie request" when
the taskqueue finally calls us back with the now stale request.
(It would have been nice if there was a way to remove a scheduled item from
a taskqueue, but that is not currently implemented in the kernel).
A real fix for this is in the works but wont make it to 6.1RELEASE
definite MFC candidate.
- Don't use a common buffer in the softc to store per-command data. Reserve
a buffer in the command itself.
- Don't allocate DMA memory for the kernel command structures when all you
really need is DMA memory for the scratch buffer embedded in them. Instead
allocate a slab for the scratch buffers and divide it up as needed.
- Call bus_dmamap_unload() at the completion of commands.
- Preserve and clear the CAM CCB status flags at completion.
- Reorder some low-level command operations to try to close races.
- Limit the simq to 32 commands for now. There are some serious problems
with the driver under load that are not well understood, so keeping the
simq lower helps avoid this. It has been tested at a higher value, but
this is a safe value that doesn't show much performance degredation.
These changes allow the driver to work reliably with >4GB of memory on i386
and amd64, and also work around deadlocks seen under very high load in
certain situations. The work-around is far from ideal, but without and
documentation it is hard to know what the right fix is.
MFC candidate
