Subject: Re: kern/1718: MAXBSIZE too low.
To: None <email@example.com>
From: Chris G Demetriou <Chris_G_Demetriou@BALVENIE.PDL.CS.CMU.EDU>
Date: 11/03/1995 16:40:08
> In netbsd-bugs you write:
> > MAXBSIZE was #defined to be MAXPHYS in 4.4BSD-Lite (and Lite2).
> > It was changed to be 16k in NetBSD. (If my memory serves me,
> > the reason given at the time was to save kernel page table space
> > on the i386.
> > This drastically reduces the effectiveness of clustering (esp.
> > write clustering), because the number of I/Os which can be combined
> > is reduced. (Coalsced I/Os must still fit into a buffer with
> > maximum size of MAXBSIZE.)
> Wait a moment, please.
> Setting MAXBSIZE=MAXPHYS=64k on my i386/sup19950927 panics at boot
That's because the i386 port doesn't properly support expanding kva
space, and doesn't statically allocate the space, either.
It's a bug in the i386 port.