New functions create - vm_object_pip_wakeup and pagedaemon_wakeup that
are used to reduce the actual number of wakeups.
New function vm_page_protect which is used in conjuction with some new
page flags to reduce the number of calls to pmap_page_protect.
Minor changes to reduce unnecessary spl nesting.
Rewrote vm_page_alloc() to improve readability.
Various other mostly cosmetic changes.
pager(). Almost completely rewrote vm_mmap(); when John gets done with
the bottom half, it will be a complete rewrite. Deprecated most use of
vm_object_setpager(). Removed side effect of setting object persist
in vm_object_enter and moved this into the pager(s). A few other
cosmetic changes.
Fixed long standing bug in freeing swap space during object collapses.
Fixed 'out of space' messages from printing out too often.
Modified to use new kmem_malloc() calling convention.
Implemented an additional stat in the swap pager struct to count the
amount of space allocated to that pager. This may be removed at some
point in the future.
Minimized unnecessary wakeups.
vm_fault.c:
Don't try to collect fault stats on 'swapped' processes - there aren't
any upages to store the stats in.
Changed read-ahead policy (again!).
vm_glue.c:
Be sure to gain a reference to the process's map before swapping.
Be sure to lose it when done.
kern_malloc.c:
Added the ability to specify if allocations are at interrupt time or
are 'safe'; this affects what types of pages can be allocated.
vm_map.c:
Fixed a variety of map lock problems; there's still a lurking bug that
will eventually bite.
vm_object.c:
Explicitly initialize the object fields rather than bzeroing the struct.
Eliminated the 'rcollapse' code and folded it's functionality into the
"real" collapse routine.
Moved an object_unlock() so that the backing_object is protected in
the qcollapse routine.
Make sure nobody fools with the backing_object when we're destroying it.
Added some diagnostic code which can be called from the debugger that
looks through all the internal objects and makes certain that they
all belong to someone.
vm_page.c:
Fixed a rather serious logic bug that would result in random system
crashes. Changed pagedaemon wakeup policy (again!).
vm_pageout.c:
Removed unnecessary page rotations on the inactive queue.
Changed the number of pages to explicitly free to just free_reserved
level.
Submitted by: John Dyson
Added hook for pmap_prefault() and use symbolic constant for new third
argument to vm_page_alloc() (vm_fault.c, various)
Changed the way that upages and page tables are held. (vm_glue.c)
Fixed architectural flaw in allocating pages at interrupt time that was
introduced with the merged cache changes. (vm_page.c, various)
Adjusted some algorithms to acheive better paging performance and to
accomodate the fix for the architectural flaw mentioned above. (vm_pageout.c)
Fixed pbuf handling problem, changed policy on handling read-behind page.
(vnode_pager.c)
Submitted by: John Dyson
much higher filesystem I/O performance, and much better paging performance. It
represents the culmination of over 6 months of R&D.
The majority of the merged VM/cache work is by John Dyson.
The following highlights the most significant changes. Additionally, there are
(mostly minor) changes to the various filesystem modules (nfs, msdosfs, etc) to
support the new VM/buffer scheme.
vfs_bio.c:
Significant rewrite of most of vfs_bio to support the merged VM buffer cache
scheme. The scheme is almost fully compatible with the old filesystem
interface. Significant improvement in the number of opportunities for write
clustering.
vfs_cluster.c, vfs_subr.c
Upgrade and performance enhancements in vfs layer code to support merged
VM/buffer cache. Fixup of vfs_cluster to eliminate the bogus pagemove stuff.
vm_object.c:
Yet more improvements in the collapse code. Elimination of some windows that
can cause list corruption.
vm_pageout.c:
Fixed it, it really works better now. Somehow in 2.0, some "enhancements"
broke the code. This code has been reworked from the ground-up.
vm_fault.c, vm_page.c, pmap.c, vm_object.c
Support for small-block filesystems with merged VM/buffer cache scheme.
pmap.c vm_map.c
Dynamic kernel VM size, now we dont have to pre-allocate excessive numbers of
kernel PTs.
vm_glue.c
Much simpler and more effective swapping code. No more gratuitous swapping.
proc.h
Fixed the problem that the p_lock flag was not being cleared on a fork.
swap_pager.c, vnode_pager.c
Removal of old vfs_bio cruft to support the past pseudo-coherency. Now the
code doesn't need it anymore.
machdep.c
Changes to better support the parameter values for the merged VM/buffer cache
scheme.
machdep.c, kern_exec.c, vm_glue.c
Implemented a seperate submap for temporary exec string space and another one
to contain process upages. This eliminates all map fragmentation problems
that previously existed.
ffs_inode.c, ufs_inode.c, ufs_readwrite.c
Changes for merged VM/buffer cache. Add "bypass" support for sneaking in on
busy buffers.
Submitted by: John Dyson and David Greenman
that this is intended for use only in floppy situations and is done at
the sacrifice of performance in that case (in ther words, this is not the
best solution, but works okay for this exceptional situation).
Submitted by: John Dyson
scheme of things, so I've changed them to be more appropriate. page in/ous
are now associated with the pager that did them. Nuked v_fault as the
only fault of interest that wouldn't be already counted in v_trap is a VM
fault, and this is counted seperately.
2) Implemented most of the remaining counters and corrected the counting of
some that were done wrong. They are all almost correct now...just a few
minor ones left to fix.
Religiously add back pmap_clear_modify() in vnode_pager_input until we figure
out why system performance isn't what we expect.
Submitted by: John Dyson (swap_pager) & David Greenman (vnode_pager)
- Delete redundant declarations.
- Add -Wredundant-declarations to Makefile.i386 so they don't come back.
- Delete sloppy COMMON-style declarations of uninitialized data in
header files.
- Add a few prototypes.
- Clean up warnings resulting from the above.
NB: ioconf.c will still generate a redundant-declaration warning, which
is unavoidable unless somebody volunteers to make `config' smarter.
improvements via the new routines pmap_qenter/pmap_qremove and pmap_kenter/
pmap_kremove. These routine allow fast mapping of pages for those
architectures that have "normal" MMUs. Also included is a fix to the
pageout daemon to properly check a queue end condition.
Submitted by: John Dyson
