Subject: Re: vmstat, iostat etc no longer work?
To: Wolfgang Solfrank <email@example.com>
From: Chris G Demetriou <Chris_G_Demetriou@ux2.sp.cs.cmu.edu>
Date: 11/15/1996 17:20:17
> Note that the code for the MACHINE_NONCONTIG
> case isn't any easier or harder than the old case, just different.
This isn't true.
in the (!MACHINE_NONCONTIG) case, the MD pmap code sets a few
variables, has to implement pmap_bootstrap_alloc(), and calls the MI
VM code. "done."
In the MACHINE_NONCONTIG case, the MD pmap code has to (at least)
implement pmap_free_pages(), pmap_virtual_space(), and
pmap_next_page(), and may also want to implement two more functions.
Essentially, pmap_virtual_space() does some of the the
variable-setting, pmap_free_pages() tells how many pages are available
to the VM system (which corresponds to most of the rest of the
variable-setting done in the !MACHINE_NONCONTIG case), but
pmap_next_page() actually does work (getting the next free page) which
is done by MI code in the !MACHINE_NONCONTIG case. It actually does
push functionality down into the MD code.
Those functions aren't "hard" to implement, but it's easier to
implement the !MACHINE_NONCONTIG case, especially if the added
functionality provided by MACHINE_NONCONTIG really isn't needed.