capable of being used for things other than swap space allocation,
and splvm would have been appropriate for only swap space allocation
and other VM things. My commit broke that (and was actually a mistake.)
previous snap. Specifically, kern_exit and kern_exec now makes a
call into the pmap module to do a very fast removal of pages from the
address space. Additionally, the pmap module now updates the PG_MAPPED
and PG_WRITABLE flags. This is an optional optimization, but helpful
on the X86.
on in the FreeBSD development, I had made a global lock around the
rlist code. This was bogus, and now the lock is maintained on a
per resource list basis. This now allows the rlist code to be used for
almost any non-interrupt level application.
``changes'' are actually not changes at all, but CVS sometimes has trouble
telling the difference.
This also includes support for second-directory compiles. This is not
quite complete yet, as `config' doesn't yet do the right thing. You can
still make it work trivially, however, by doing the following:
rm /sys/compile
mkdir /usr/obj/sys/compile
ln -s M-. /sys/compile
cd /sys/i386/conf
config MYKERNEL
cd ../../compile/MYKERNEL
ln -s /sys @
rm machine
ln -s @/i386/include machine
make depend
make
set improves performance and fixes the following problems (description
from John Dyson):
1. Growing swap space problem in both static usage and
in situations with lots of fork/execs in heavy paging
situations.
2. Sparse swap space allocation (internal fragmentation.)
3. General swap_pager slowness.
Additionally, the new swap_pager also provides hooks for multi-page
I/O that is currently being developed (in early testing phases.)
Problem #1 is a result of a problem where objects cannot be collapsed
once a pager has been allocated for them. This problem has been solved
by relaxing the restriction by allowing the pages contained in a shadow
object's pager be copied to the parent object's pager. The copy is
afforded by manipulating pointers to the disk blocks on the swap space.
Since an improved swap_pager has already been developed with the data
structures to support the copy operation, this new swap_pager has been
introduced. Also, shadow object bypass in the collapse code has been
enhanced to support checking for pages on disk. The vm_pageout daemon
has also been modified to defer creation of an object's pager when the
object's shadow is paging. This allows efficient immediate collapsing
of a shadow into a parent object under many circumstances without the
creation of an intermediate pager.
Problem #2 is solved by the allocation data structures and algorithms
in the new swap_pager. Additionally, a newer version of this new swap_pager
is being tested that permits multiple page I/O and mitigation of the
fragmentation problems associated with allocation of large contiguous blocks
of swap space.
Problem #3 is addressed by better algorithms and a fix of a couple of bugs
in the swap_pager. Additionally, this new pager has a growth path allowing
multi-page inputs from disk. Approximately 50% performance improvement can
be expected under certain circumstances when using this pager in the standard
single page mode.
(Actually, I've seen more like twice the speed in my tests. -DLG)
a binary link-kit. Make all non-optional options (pagers, procfs) standard,
and update LINT to reflect new symtab requirements.
NB: -Wtraditional will henceforth be forgotten. This editing pass was
primarily intended to detect any constructions where the old code might
have been relying on traditional C semantics or syntax. These were all
fixed, and the result of fixing some of them means that -Wall is now a
realistic possibility within a few weeks.
