I've fixed the compilation for ALL kernels.
2017-10-10 17:34 GMT+02:00 Michael <macallan%netbsd.org@localhost
> I tried sequential reads ( dd if=/dev/rwd0c ... ) and throughput took a
> significant hit. I used to get about 120MB/s with the siisata, now it
> fluctuates between 80 and 90MB/s, ahcisata dropped from about 80MB/s to
> 70MB/s. Both spinning rust of varying vintage.
> I should probably do a bonnie run on either one before & after to see
> if there's any change in random access.
I've seen this on one of my disks, too. It seems it's much slower in NCQ mode. I think the firmware might not utilise the disk cache properly when in NCQ mode.
You can try switching it off via sysctl, hw.wdX.use_ncq. You can also try to turn off use_ncq_prio if that makes any difference.
We might need to introduce some heuristics for this.