about the "wdrain" state

[Jimmy Olgeni]

Hi!

I have a Compaq DL380 G2 server with a SmartArray 5i controller
running 4.8-RELEASE.

When I move a lot of data on the disk (like untarring a new ports
collection or /usr/src/) the process works fine for a while, then
takes a long pause, then restarts again. When it "pauses", pressing ^T
shows it's in the "wdrain" state, which looks related to waiting for
the disk to finish some write operations. Unfortunately, the 5i
controller has a somewhat poor performance by itself so that may be
the cause.

Are there any kernel tunables that I could change to at least "spread"
the pauses over many small intervals, rather than locking the process
for a few seconds? The volume is using softupdates, I thought about
changing kern.filedelay and friends but I'd like to know if there are
sensibile values to put in before I fry the production server :)

-- 
jimmy