Subject: BUFQ_FCFS for XENU kernels?
To: None <firstname.lastname@example.org>
From: Thor Lancelot Simon <email@example.com>
Date: 03/01/2006 15:19:13
I *think* requests passing through xbd will always be sorted by the
underlying device driver in the dom0 OS. Certainly if the requests
are heading for something like a vnd, sorting them in the domU kernel
is not the right thing to do, since they could then be sorted *three*
But I cannot build a domU kernel (on the 3.0) branch with "options BUFQ_FCFS"
defined. The other BUFQ options seem to work (READPRIO, PRIOCSCAN) but FCFS
produces a compile-time error in xbd. I do not quite see why.
Does xbd already default to BUFQ_FCFS? We should either make it so or
make BUFQ_FCFS the default with "options BUFQ_FCFS" in the XENU kernel.
Certainly vnd itself should default to BUFQ_FCFS. Ultimately, in a stack
of NetBSD domU on NetBSD dom0, with xbd and vnd in the middle, only the
actual lowest-layer disk driver should sort.
Thor Lancelot Simon firstname.lastname@example.org
"We cannot usually in social life pursue a single value or a single moral
aim, untroubled by the need to compromise with others." - H.L.A. Hart