Commit Graph

159 Commits

Author SHA1 Message Date
John Dyson
2d8acc0f4a VM level code cleanups.
1)	Start using TSM.
	Struct procs continue to point to upages structure, after being freed.
	Struct vmspace continues to point to pte object and kva space for kstack.
	u_map is now superfluous.
2)	vm_map's don't need to be reference counted.  They always exist either
	in the kernel or in a vmspace.  The vmspaces are managed by reference
	counts.
3)	Remove the "wired" vm_map nonsense.
4)	No need to keep a cache of kernel stack kva's.
5)	Get rid of strange looking ++var, and change to var++.
6)	Change more data structures to use our "zone" allocator.  Added
	struct proc, struct vmspace and struct vnode.  This saves a significant
	amount of kva space and physical memory.  Additionally, this enables
	TSM for the zone managed memory.
7)	Keep ioopt disabled for now.
8)	Remove the now bogus "single use" map concept.
9)	Use generation counts or id's for data structures residing in TSM, where
	it allows us to avoid unneeded restart overhead during traversals, where
	blocking might occur.
10)	Account better for memory deficits, so the pageout daemon will be able
	to make enough memory available (experimental.)
11)	Fix some vnode locking problems. (From Tor, I think.)
12)	Add a check in ufs_lookup, to avoid lots of unneeded calls to bcmp.
	(experimental.)
13)	Significantly shrink, cleanup, and make slightly faster the vm_fault.c
	code.  Use generation counts, get rid of unneded collpase operations,
	and clean up the cluster code.
14)	Make vm_zone more suitable for TSM.

This commit is partially as a result of discussions and contributions from
other people, including DG, Tor Egge, PHK, and probably others that I
have forgotten to attribute (so let me know, if I forgot.)

This is not the infamous, final cleanup of the vnode stuff, but a necessary
step.  Vnode mgmt should be correct, but things might still change, and
there is still some missing stuff (like ioopt, and physical backing of
non-merged cache files, debugging of layering concepts.)
1998-01-22 17:30:44 +00:00
John Dyson
4722175765 Tie up some loose ends in vnode/object management. Remove an unneeded
config option in pmap.  Fix a problem with faulting in pages.  Clean-up
some loose ends in swap pager memory management.

The system should be much more stable, but all subtile bugs aren't fixed yet.
1998-01-17 09:17:02 +00:00
John Dyson
925a3a419a Fix some vnode management problems, and better mgmt of vnode free list.
Fix the UIO optimization code.
Fix an assumption in vm_map_insert regarding allocation of swap pagers.
Fix an spl problem in the collapse handling in vm_object_deallocate.
When pages are freed from vnode objects, and the criteria for putting
the associated vnode onto the free list is reached, either put the
vnode onto the list, or put it onto an interrupt safe version of the
list, for further transfer onto the actual free list.
Some minor syntax changes changing pre-decs, pre-incs to post versions.
Remove a bogus timeout (that I added for debugging) from vn_lock.

PHK will likely still have problems with the vnode list management, and
so do I, but it is better than it was.
1998-01-12 01:46:33 +00:00
John Dyson
95e5e988e0 Make our v_usecount vnode reference count work identically to the
original BSD code.  The association between the vnode and the vm_object
no longer includes reference counts.  The major difference is that
vm_object's are no longer freed gratuitiously from the vnode, and so
once an object is created for the vnode, it will last as long as the
vnode does.

When a vnode object reference count is incremented, then the underlying
vnode reference count is incremented also.  The two "objects" are now
more intimately related, and so the interactions are now much less
complex.

When vnodes are now normally placed onto the free queue with an object still
attached.  The rundown of the object happens at vnode rundown time, and
happens with exactly the same filesystem semantics of the original VFS
code.  There is absolutely no need for vnode_pager_uncache and other
travesties like that anymore.

A side-effect of these changes is that SMP locking should be much simpler,
the I/O copyin/copyout optimizations work, NFS should be more ponderable,
and further work on layered filesystems should be less frustrating, because
of the totally coherent management of the vnode objects and vnodes.

Please be careful with your system while running this code, but I would
greatly appreciate feedback as soon a reasonably possible.
1998-01-06 05:26:17 +00:00
John Dyson
2be70f79f6 Lots of improvements, including restructring the caching and management
of vnodes and objects.  There are some metadata performance improvements
that come along with this.  There are also a few prototypes added when
the need is noticed.  Changes include:

1) Cleaning up vref, vget.
2) Removal of the object cache.
3) Nuke vnode_pager_uncache and friends, because they aren't needed anymore.
4) Correct some missing LK_RETRY's in vn_lock.
5) Correct the page range in the code for msync.

Be gentle, and please give me feedback asap.
1997-12-29 00:25:11 +00:00
John Dyson
b44e4b7a2b Support running with inadequate swap space. Additionally, the code
will complain with a suggestion of increasing it.
1997-12-24 15:05:25 +00:00
John Dyson
ceb0cf87e8 Support an optional, sysctl enabled feature of idle process swapout. This
is apparently useful for large shell systems, or systems  with long running
idle processes.  To enable the feature:

	sysctl -w vm.swap_idle_enabled=1

Please note that some of the other vm sysctl variables have been renamed
to be more accurate.
Submitted by:	Much of it from Matt Dillon <dillon@best.net>
1997-12-06 02:23:36 +00:00
John Dyson
70111b9016 Add new (very useful) tunable for pageout daemon. The flag changes
the maximum pageout rate:

sysctl -w vm.vm_maxlaunder=n

 1 < n < inf.

If paging heavily on large systems, it is likely that a performance
improvement can be achieved by increasing the parameter.  On a large
system, the parm is 32, but numbers as large as 128 can make a big
difference.  If paging is expensive, you might try decreasing the
number to 1-8.
1997-12-05 05:41:06 +00:00
John Dyson
12ac6a1dbb Support applications that need to resist or deny use of swap space.
sysctl -w vm.defer_swap_pageouts=1
	Causes the system to resist the use of swap space.  In low memory
	conditions, performance will decrease.
sysctl -w vm.disable_swap_pageouts=1
	Causes the system to mostly disable the use of swap space.  In
	low memory conditions, the system will likely start killing
	processes.
1997-12-04 19:00:56 +00:00
John Dyson
5985940e79 Support garbage collecting the pmap pv entries. The management doesn't
happen until the system would have nearly failed anyway, so no signficant
overhead is added.  This helps large systems with lots of processes.
1997-10-25 02:41:56 +00:00
John Dyson
7e00649986 Improve management of pages moving from the inactive to active queue. Additionally,
add some much needed comments.
1997-10-06 02:48:16 +00:00
Bruce Evans
79624e2147 Removed unused #includes. 1997-09-01 03:17:34 +00:00
John Dyson
dc2efb2766 Add the ability for the pageout daemon to measure stats on memory usage before
the system is out of memory.  The daemon does a minimal amount of work that
increases as the system becomes more likely to run out of memory and page in/out.

The default tuning is fairly low in background CPU usage, and sysctl variables
have been added to enable flexable operation.  This is an experimental feature
that will likely be changed and improved over time.
1997-07-27 04:49:19 +00:00
Bruce Evans
2f558c3e59 Removed a wrong LK_INTERLOCK flag. 1997-02-27 15:38:41 +00:00
Peter Wemm
6875d25465 Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.
1997-02-22 09:48:43 +00:00
John Dyson
996c772f58 This is the kernel Lite/2 commit. There are some requisite userland
changes, so don't expect to be able to run the kernel as-is (very well)
without the appropriate Lite/2 userland changes.

The system boots and can mount UFS filesystems.

Untested: ext2fs, msdosfs, NFS
Known problems: Incorrect Berkeley ID strings in some files.
		Mount_std mounts will not work until the getfsent
		library routine is changed.

Reviewed by:	various people
Submitted by:	Jeffery Hsu <hsu@freebsd.org>
1997-02-10 02:22:35 +00:00
John Dyson
afa07f7e83 Change the map entry flags from bitfields to bitmasks. Allows
for some code simplification.
1997-01-16 04:16:22 +00:00
Bruce Evans
16a02c1105 Removed redundant spl0()'s from kernel processes. They were work-arounds
for a bug in fork().
1997-01-15 19:05:08 +00:00
Jordan K. Hubbard
1130b656e5 Make the long-awaited change from $Id$ to $FreeBSD$
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore.  This update would have been
insane otherwise.
1997-01-14 07:20:47 +00:00
John Dyson
d4a272db61 Slightly correct the code that moves pages from the active to the
inactive queue.  This is only a minor performance improvement, but will
not affect perf on machines that don't have ref bits.
1997-01-11 07:22:24 +00:00
John Dyson
106031ef73 Undo the collapse breakage (swap space usage problem.) 1997-01-03 17:02:28 +00:00
John Dyson
3c018e7214 Guess what? We left alot of the old collapse code that is not needed
anymore with the "full" collapse fix that we added about 1yr ago!!!  The
code has been removed by optioning it out for now, so we can put it back
in ASAP if any problems are found.
1997-01-01 04:45:05 +00:00
John Dyson
e0c5a895f1 Make the kernel smaller with at worst a neutral effect on perf by
de-inlining some VM calls.  (Actually, I measured a small improvement.)
1996-11-28 23:15:07 +00:00
John Dyson
a2f4a84696 Reviewed by:
Submitted by:
Obtained from:
1996-09-28 03:33:40 +00:00
John Dyson
5070c7f8c5 Addition of page coloring support. Various levels of coloring are afforded.
The default level works with minimal overhead, but one can also enable
full, efficient use of a 512K cache.  (Parameters can be generated
to support arbitrary cache sizes also.)
1996-09-08 20:44:49 +00:00
John Dyson
67bf686897 Backed out the recent changes/enhancements to the VM code. The
problem with the 'shell scripts' was found, but there was a 'strange'
problem found with a 486 laptop that we could not find.  This commit
backs the code back to 25-jul, and will be re-entered after the snapshot
in smaller (more easily tested) chunks.
1996-07-30 03:08:57 +00:00
John Dyson
4f4d35edf0 This commit is meant to solve a couple of VM system problems or
performance issues.

	1) The pmap module has had too many inlines, and so the
	   object file is simply bigger than it needs to be.
	   Some common code is also merged into subroutines.
	2) Removal of some *evil* PHYS_TO_VM_PAGE macro calls.
	   Unfortunately, a few have needed to be added also.
	   The removal caused the need for more vm_page_lookups.
	   I added lookup hints to minimize the need for the
	   page table lookup operations.
	3) Removal of some bogus performance improvements, that
	   mostly made the code more complex (tracking individual
	   page table page updates unnecessarily).  Those improvements
	   actually hurt 386 processors perf (not that people who
	   worry about perf use 386 processors anymore :-)).
	4) Changed pv queue manipulations/structures to be TAILQ's.
	5) The pv queue code has had some performance problems since
	   day one.  Some significant scalability issues are resolved
	   by threading the pv entries from the pmap AND the physical
	   address instead of just the physical address.  This makes
	   certain pmap operations run much faster.  This does
	   not affect most micro-benchmarks, but should help loaded system
	   performance *significantly*.  DG helped and came up with most
	   of the solution for this one.
	6) Most if not all pmap bit operations follow the pattern:
		pmap_test_bit();
		pmap_clear_bit();
	   That made for twice the necessary pv list traversal.   The
	   pmap interface now supports only pmap_tc_bit type operations:
	   pmap_[test/clear]_modified, pmap_[test/clear]_referenced.
	   Additionally, the modified routine now takes a vm_page_t arg
	   instead of a phys address.  This eliminates a PHYS_TO_VM_PAGE
	   operation.
	7) Several rewrites of routines that contain redundant code to
	   use common routines, so that there is a greater likelihood of
	   keeping the cache footprint smaller.
1996-07-27 03:24:10 +00:00
John Dyson
502ba6e4a8 Back-off on the previous commit, specifically remove the look-ahead
optimization on the active queue scan.  I will do this correctly later.
1996-07-08 03:22:55 +00:00
John Dyson
c8c4b40cca Fix a problem with the pageout daemon RSS limiting, where it degrades
performance to LRU or worse when RSS limiting takes effect.  Also,
make an end condition in the active queue scan more efficient in the
case where pages are removed from the active queue as a side effect
of a pmap operation.
1996-07-08 02:25:53 +00:00
David Greenman
01155bd720 Make sure we have an object in the map entry before trying to trim pages
from it.
1996-06-29 09:17:17 +00:00
John Dyson
38efa82b23 This commit does a couple of things:
Re-enables the RSS limiting, and the routine is now tail-recursive,
	making it much more safe (eliminates the possiblity of kernel stack
	overflow.) Also, the RSS limiting is a little more intelligent about
	finding the likely objects that are pushing the process over the limit.

	Added some sysctls that help with VM system tuning.

New sysctl features:
	1)	Enable/disable lru pageout algorithm.
		vm.pageout_algorithm = 0, default algorithm that works
			well, especially using X windows and heavy
			memory loading.  Can have adverse effects,
			sometimes slowing down program loading.

		vm.pageout_algorithm = 1, close to true LRU.  Works much
			better than clock, etc.  Does not work as well as
			the default algorithm in general.  Certain memory
			"malloc" type benchmarks work a little better with
			this setting.

		Please give me feedback on the performance results
		associated with these.

	2)	Enable/disable swapping.
		vm.swapping_enabled = 1, default.

		vm.swapping_enabled = 0, useful for cases where swapping
			degrades performance.

		The config option "NO_SWAPPING" is still operative, and
		takes precedence over the sysctl.  If "NO_SWAPPING" is
		specified, the sysctl still exists, but "vm.swapping_enabled"
		is hard-wired to "0".

Each of these can be changed "on the fly."
1996-06-26 05:39:27 +00:00
John Dyson
a001376dc3 Remove RSS limiting until I rewrite the code to be non-recursive. The
code can overrun the kernel stack under very stressful conditions.
1996-06-24 04:30:24 +00:00
John Dyson
ef743ce6ed Several bugfixes/improvements:
1) Make it much less likely to miss a wakeup in vm_page_free_wakeup
	2) Create a new entry point into pmap: pmap_ts_referenced, eliminates
	   the need to scan the pv lists twice in many cases.  Perhaps there
	   is alot more to do here to work on minimizing pv list manipulation
	3) Minor improvements to vm_pageout including the use of pmap_ts_ref.
	4) Major changes and code improvement to pmap.  This code has had
	   several serious bugs in page table page manipulation.  In order
	   to simplify the problem, and hopefully solve it for once and all,
	   page table pages are no longer "managed" with the pv list stuff.
	   Page table pages are only (mapped and held/wired) or
	   (free and unused) now.  Page table pages are never inactive,
	   active or cached.  These changes have probably fixed the
	   hold count problems, but if they haven't, then the code is
	   simpler anyway for future bugfixing.
	5) The pmap code has been sorely in need of re-organization, and I
	   have taken a first (of probably many) steps.  Please tell me
	   if you have any ideas.
1996-06-17 03:35:40 +00:00
John Dyson
f35329ac0f This commit is dual-purpose, to fix more of the pageout daemon
queue corruption problems, and to apply Gary Palmer's code cleanups.
David Greenman helped with these problems also.  There is still
a hang problem using X in small memory machines.
1996-05-31 00:38:04 +00:00
John Dyson
545901f794 Correct some unfortunately chosen constants, otherwise, not enough
pages are calculated for deferred allocation of swap pager data structures.
This is a follow-on to the previous commit to this file.
1996-05-29 06:33:30 +00:00
John Dyson
b182ec9eb4 After careful review by David Greenman and myself, David had found a
case where blocking can occur, thereby giving other process's a chance
to modify the queue where a page resides.  This could cause numerous
process and system failures.
1996-05-29 05:15:33 +00:00
John Dyson
85a376eb93 Fix a couple of problems in the pageout_scan routine. First, there is
a condition when blocking can occur, and the daemon did not check properly
for a page remaining on the expected queue.  Additionally, the inactive
target was being set much too large for small memory machines.  It is now
being calculated based upon the amount of user memory available on every
pageout daemon run.  Another problem was that if memory was very low, the
pageout daemon could fail repeatedly to traverse the inactive queue.
1996-05-26 07:52:09 +00:00
John Dyson
1eeaa1e31f Add apparently needed splvm protection to the active queue, and eliminate
an unnecessary test for dirty pages if it is already known to be dirty.
1996-05-24 05:19:15 +00:00
John Dyson
b18bfc3da7 This set of commits to the VM system does the following, and contain
contributions or ideas from Stephen McKay <syssgm@devetir.qld.gov.au>,
Alan Cox <alc@cs.rice.edu>, David Greenman <davidg@freebsd.org> and me:

	More usage of the TAILQ macros.  Additional minor fix to queue.h.
	Performance enhancements to the pageout daemon.
		Addition of a wait in the case that the pageout daemon
		has to run immediately.
		Slightly modify the pageout algorithm.
	Significant revamp of the pmap/fork code:
		1) PTE's and UPAGES's are NO LONGER in the process's map.
		2) PTE's and UPAGES's reside in their own objects.
		3) TOTAL elimination of recursive page table pagefaults.
		4) The page directory now resides in the PTE object.
		5) Implemented pmap_copy, thereby speeding up fork time.
		6) Changed the pv entries so that the head is a pointer
		   and not an entire entry.
		7) Significant cleanup of pmap_protect, and pmap_remove.
		8) Removed significant amounts of machine dependent
		   fork code from vm_glue.  Pushed much of that code into
		   the machine dependent pmap module.
		9) Support more completely the reuse of already zeroed
		   pages (Page table pages and page directories) as being
		   already zeroed.
	Performance and code cleanups in vm_map:
		1) Improved and simplified allocation of map entries.
		2) Improved vm_map_copy code.
		3) Corrected some minor problems in the simplify code.
	Implemented splvm (combo of splbio and splimp.)  The VM code now
		seldom uses splhigh.
	Improved the speed of and simplified kmem_malloc.
	Minor mod to vm_fault to avoid using pre-zeroed pages in the case
		of objects with backing objects along with the already
		existant condition of having a vnode.  (If there is a backing
		object, there will likely be a COW...  With a COW, it isn't
		necessary to start with a pre-zeroed page.)
	Minor reorg of source to perhaps improve locality of ref.
1996-05-18 03:38:05 +00:00
Bruce Evans
bd105bb750 Fixed a spl hog. The vmdaemon process ran entirely at splhigh. It
sometimes disabled clock interrupts for 60 msec or more on a P133.
Clock interrupts were lost ...

Reviewed by:	dyson
1996-04-11 21:05:25 +00:00
John Dyson
30dcfc09f2 VM performance improvements, and reorder some operations in VM fault
in anticipation of a fix in pmap that will allow the mlock system call to work
without panicing the system.
1996-03-28 04:53:28 +00:00
Jeffrey Hsu
1b67ec6de9 For Lite2: proc LIST changes.
Reviewed by:	 davidg & bde
1996-03-11 06:11:43 +00:00
John Dyson
6ac5bfdb3a Fix a calculation for a paging parameter. 1996-03-09 06:53:27 +00:00
David Greenman
5afce28270 Add a "NO_SWAPPING" option to disable swapping. This was originally done
to help diagnose a problem on wcarchive (where the kernel stack was
sometimes not present), but is useful in its own right since swapping
actually reduces performance on some systems (such as wcarchive).
Note: swapping in this context means making the U pages pageable and has
nothing to do with generic VM paging, which is unaffected by this option.

Reviewed by:	 <dyson>
1996-02-22 10:57:37 +00:00
David Greenman
729b1e5149 Improved killproc() log message and made it and the other similar message
tolerant of p_ucred being invalid. Starting using killproc() where
appropriate.
1996-01-31 12:44:33 +00:00
John Dyson
bd7e5f992e Eliminated many redundant vm_map_lookup operations for vm_mmap.
Speed up for vfs_bio -- addition of a routine bqrelse to greatly diminish
	overhead for merged cache.
Efficiency improvement for vfs_cluster.  It used to do alot of redundant
	calls to cluster_rbuild.
Correct the ordering for vrele of .text and release of credentials.
Use the selective tlb update for 486/586/P6.
Numerous fixes to the size of objects allocated for files.  Additionally,
	fixes in the various pagers.
Fixes for proper positioning of vnode_pager_setsize in msdosfs and ext2fs.
Fixes in the swap pager for exhausted resources.  The pageout code
	will not as readily thrash.
Change the page queue flags (PG_ACTIVE, PG_INACTIVE, PG_FREE, PG_CACHE) into
	page queue indices (PQ_ACTIVE, PQ_INACTIVE, PQ_FREE, PQ_CACHE),
	thereby improving efficiency of several routines.
Eliminate even more unnecessary vm_page_protect operations.
Significantly speed up process forks.
Make vm_object_page_clean more efficient, thereby eliminating the pause
	that happens every 30seconds.
Make sequential clustered writes B_ASYNC instead of B_DELWRI even in the
	case of filesystems mounted async.
Fix a panic with busy pages when write clustering is done for non-VMIO
	buffers.
1996-01-19 04:00:31 +00:00
Poul-Henning Kamp
f708ef1b9e Another mega commit to staticize things. 1995-12-14 09:55:16 +00:00
John Dyson
a316d390bd Changes to support 1Tb filesizes. Pages are now named by an
(object,index) pair instead of (object,offset) pair.
1995-12-11 04:58:34 +00:00
David Greenman
efeaf95a41 Untangled the vm.h include file spaghetti. 1995-12-07 12:48:31 +00:00
Poul-Henning Kamp
3af768903d Remove unused vars & funcs, make things static, protoize a little bit. 1995-11-20 12:20:02 +00:00
John Dyson
aef922f514 Greatly simplify the msync code. Eliminate complications in vm_pageout
for msyncing.  Remove a bug that manifests itself primarily on NFS
(the dirty range on the buffers is not set on msync.)
1995-11-05 20:46:03 +00:00
John Dyson
a91c5a7ecd Get rid of machine-dependent NBPG and replace with PAGE_SIZE. 1995-10-23 05:35:48 +00:00
David Greenman
cd41fc123e Fix argument passing to the "freeer" routine. Added some prototypes. (bde)
Moved extern declaration of swap_pager_full into swap_pager.h and out of
the various files that reference it. (davidg)

Submitted by:	bde & davidg
1995-10-07 19:02:56 +00:00
Poul-Henning Kamp
a5eb0e27e4 Avoid a 64bit divide. 1995-10-06 09:42:11 +00:00
David Greenman
4590fd3a2a Fixed init functions argument type - caddr_t -> void *. Fixed a couple of
compiler warnings.
1995-09-09 18:10:37 +00:00
Julian Elischer
2b14f991e6 Reviewed by: julian with quick glances by bruce and others
Submitted by:	terry (terry lambert)
This is  a composite of 3 patch sets submitted by terry.
they are:
New low-level init code that supports loadbal modules better
some cleanups in the namei code to help terry in 16-bit character support
some changes to the mount-root code to make it a little more
modular..

NOTE: mounting root off cdrom or NFS MIGHT be broken as I haven't been able
to test those cases..

certainly mounting root of disk still works just fine..
mfs should work but is untested. (tomorrows task)

The low level init stuff includes a total rewrite of init_main.c
to make it possible for new modules to have an init phase by simply
adding an entry to a TEXT_SET (or is it DATA_SET) list. thus a new module can
be added to the kernel without editing any other files other than the
'files' file.
1995-08-28 09:19:25 +00:00
David Greenman
24a1cce34f NOTE: libkvm, w, ps, 'top', and any other utility which depends on struct
proc or any VM system structure will have to be rebuilt!!!

Much needed overhaul of the VM system. Included in this first round of
changes:

1) Improved pager interfaces: init, alloc, dealloc, getpages, putpages,
   haspage, and sync operations are supported. The haspage interface now
   provides information about clusterability. All pager routines now take
   struct vm_object's instead of "pagers".

2) Improved data structures. In the previous paradigm, there is constant
   confusion caused by pagers being both a data structure ("allocate a
   pager") and a collection of routines. The idea of a pager structure has
   escentially been eliminated. Objects now have types, and this type is
   used to index the appropriate pager. In most cases, items in the pager
   structure were duplicated in the object data structure and thus were
   unnecessary. In the few cases that remained, a un_pager structure union
   was created in the object to contain these items.

3) Because of the cleanup of #1 & #2, a lot of unnecessary layering can now
   be removed. For instance, vm_object_enter(), vm_object_lookup(),
   vm_object_remove(), and the associated object hash list were some of the
   things that were removed.

4) simple_lock's removed. Discussion with several people reveals that the
   SMP locking primitives used in the VM system aren't likely the mechanism
   that we'll be adopting. Even if it were, the locking that was in the code
   was very inadequate and would have to be mostly re-done anyway. The
   locking in a uni-processor kernel was a no-op but went a long way toward
   making the code difficult to read and debug.

5) Places that attempted to kludge-up the fact that we don't have kernel
   thread support have been fixed to reflect the reality that we are really
   dealing with processes, not threads. The VM system didn't have complete
   thread support, so the comments and mis-named routines were just wrong.
   We now use tsleep and wakeup directly in the lock routines, for instance.

6) Where appropriate, the pagers have been improved, especially in the
   pager_alloc routines. Most of the pager_allocs have been rewritten and
   are now faster and easier to maintain.

7) The pagedaemon pageout clustering algorithm has been rewritten and
   now tries harder to output an even number of pages before and after
   the requested page. This is sort of the reverse of the ideal pagein
   algorithm and should provide better overall performance.

8) Unnecessary (incorrect) casts to caddr_t in calls to tsleep & wakeup
   have been removed. Some other unnecessary casts have also been removed.

9) Some almost useless debugging code removed.

10) Terminology of shadow objects vs. backing objects straightened out.
    The fact that the vm_object data structure escentially had this
    backwards really confused things. The use of "shadow" and "backing
    object" throughout the code is now internally consistent and correct
    in the Mach terminology.

11) Several minor bug fixes, including one in the vm daemon that caused
    0 RSS objects to not get purged as intended.

12) A "default pager" has now been created which cleans up the transition
    of objects to the "swap" type. The previous checks throughout the code
    for swp->pg_data != NULL were really ugly. This change also provides
    the rudiments for future backing of "anonymous" memory by something
    other than the swap pager (via the vnode pager, for example), and it
    allows the decision about which of these pagers to use to be made
    dynamically (although will need some additional decision code to do
    this, of course).

13) (dyson) MAP_COPY has been deprecated and the corresponding "copy
    object" code has been removed. MAP_COPY was undocumented and non-
    standard. It was furthermore broken in several ways which caused its
    behavior to degrade to MAP_PRIVATE. Binaries that use MAP_COPY will
    continue to work correctly, but via the slightly different semantics
    of MAP_PRIVATE.

14) (dyson) Sharing maps have been removed. It's marginal usefulness in a
    threads design can be worked around in other ways. Both #12 and #13
    were done to simplify the code and improve readability and maintain-
    ability. (As were most all of these changes)

TODO:

1) Rewrite most of the vnode pager to use VOP_GETPAGES/PUTPAGES. Doing
   this will reduce the vnode pager to a mere fraction of its current size.

2) Rewrite vm_fault and the swap/vnode pagers to use the clustering
   information provided by the new haspage pager interface. This will
   substantially reduce the overhead by eliminating a large number of
   VOP_BMAP() calls. The VOP_BMAP() filesystem interface should be
   improved to provide both a "behind" and "ahead" indication of
   contiguousness.

3) Implement the extended features of pager_haspage in swap_pager_haspage().
   It currently just says 0 pages ahead/behind.

4) Re-implement the swap device (swstrategy) in a more elegant way, perhaps
   via a much more general mechanism that could also be used for disk
   striping of regular filesystems.

5) Do something to improve the architecture of vm_object_collapse(). The
   fact that it makes calls into the swap pager and knows too much about
   how the swap pager operates really bothers me. It also doesn't allow
   for collapsing of non-swap pager objects ("unnamed" objects backed by
   other pagers).
1995-07-13 08:48:48 +00:00
David Greenman
6306c897b5 swapout_threads() -> swapout_procs(). 1995-07-10 08:53:22 +00:00
Rodney W. Grimes
9b2e535452 Remove trailing whitespace. 1995-05-30 08:16:23 +00:00
David Greenman
61f5d51062 Changes to fix the following bugs:
1) Files weren't properly synced on filesystems other than UFS. In some
   cases, this lead to lost data. Most likely would be noticed on NFS.
   The fix is to make the VM page sync/object_clean general rather than
   in each filesystem.
2) Mixing regular and mmaped file I/O on NFS was very broken. It caused
   chunks of files to end up as zeroes rather than the intended contents.
   The fix was to fix several race conditions and to kludge up the
   "b_dirtyoff" and "b_dirtyend" that NFS relies upon - paying attention
   to page modifications that occurred via the mmapping.

Reviewed by:	David Greenman
Submitted by:	John Dyson
1995-05-21 21:39:31 +00:00
David Greenman
ee3a64c992 Changed "handle" from type caddr_t to void *; "handle" is several different
types of pointers, and "char *" is a bad choice for the type.
1995-05-10 18:56:09 +00:00
David Greenman
4c1f8ee9b8 Fixed a logic bug that caused the vmdaemon to not wake up when intended.
Submitted by:	John Dyson
1995-04-17 10:00:55 +00:00
David Greenman
7c0414d074 Removed obsolete/unused variable declarations. Killed externs and included
appropriate include files.
1995-04-16 14:12:15 +00:00
David Greenman
c3cb3e12f5 Moved some zero-initialized variables into .bss. Made code intended to be
called only from DDB #ifdef DDB. Removed some completely unused globals.
1995-04-16 12:56:22 +00:00
David Greenman
f6b04d2bfb Changes from John Dyson and myself:
Fixed remaining known bugs in the buffer IO and VM system.

vfs_bio.c:
Fixed some race conditions and locking bugs. Improved performance
by removing some (now) unnecessary code and fixing some broken
logic.
Fixed process accounting of # of FS outputs.
Properly handle NFS interrupts (B_EINTR).

(various)
Replaced calls to clrbuf() with calls to an optimized routine
called vfs_bio_clrbuf().

(various FS sync)
Sync out modified vnode_pager backed pages.

ffs_vnops.c:
Do two passes: Sync out file data first, then indirect blocks.

vm_fault.c:
Fixed deadly embrace caused by acquiring locks in the wrong order.

vnode_pager.c:
Changed to use buffer I/O system for writing out modified pages. This
should fix the problem with the modification date previous not getting
updated. Also dramatically simplifies the code. Note that this is
going to change in the future and be implemented via VOP_PUTPAGES().

vm_object.c:
Fixed a pile of bugs related to cleaning (vnode) objects. The performance
of vm_object_page_clean() is terrible when dealing with huge objects,
but this will change when we implement a binary tree to keep the object
pages sorted.

vm_pageout.c:
Fixed broken clustering of pageouts. Fixed race conditions and other
lockup style bugs in the scanning of pages. Improved performance.
1995-04-09 06:03:56 +00:00
David Greenman
17c4c40800 Fixed typo...using wrong variable in page_shortage calculation. 1995-03-28 05:58:35 +00:00
David Greenman
0bb3a0d2f4 Fixed "pages freed by daemon" statistic (again). 1995-03-28 05:35:29 +00:00
Bruce Evans
b5e8ce9f12 Add and move declarations to fix all of the warnings from `gcc -Wimplicit'
(except in netccitt, netiso and netns) and most of the warnings from
`gcc -Wnested-externs'.  Fix all the bugs found.  There were no serious
ones.
1995-03-16 18:17:34 +00:00
David Greenman
61ca29b0e5 Deleted vm_object_setpager(). 1995-03-12 07:58:29 +00:00
David Greenman
f919ebde54 Various changes from John and myself that do the following:
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.
1995-03-01 23:30:04 +00:00
Bruce Evans
4f9fb771a5 Don't use __P(()) in a function definition. 1995-02-25 18:39:04 +00:00
David Greenman
6f2b142ed8 vm_page.c:
Use request==VM_ALLOC_NORMAL rather than object!=kmem_object in deciding
if the caller is "important" in vm_page_alloc(). Also established a new
low threshold for non-interrupt allocations via cnt.v_interrupt_free_min.

vm_pageout.c:
Various algorithmic cleanup. Some calculations simplified. Initialize
cnt.v_interrupt_free_min to 2 pages.

Submitted by:	John Dyson
1995-02-22 10:27:24 +00:00
David Greenman
c0503609a0 Only do object paging_in_progress wakeups if someone is waiting on this
condition.

Submitted by:	John Dyson
1995-02-22 09:15:35 +00:00
David Greenman
0c1dacbc5c Moved ACT_MAX, ACT_ADVANCE, and ACT_DECLINE to vm_page.h. 1995-02-20 23:35:45 +00:00
Poul-Henning Kamp
d2fc53150b YF fix. 1995-02-14 06:14:28 +00:00
David Greenman
1ed81ef2fa Minor algorithmic adjustments that reduce the CPU consumption of the
pagedaemon in half while not reducing its effectiveness.

Submitted by:	me & John
1995-02-09 07:41:42 +00:00
David Greenman
a1f6d91cc2 swap_pager.c:
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
1995-02-02 09:09:15 +00:00
David Greenman
8f895206ff Completed the fix for attempting to page out pages via the device_pager.
Submitted by:	John Dyson
1995-01-28 02:02:25 +00:00
David Greenman
6d40c3d394 Added ability to detect sequential faults and DTRT. (swap_pager.c)
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
1995-01-24 10:14:09 +00:00
David Greenman
480dff540b Fixed some formatting weirdness that I overlooked in the previous commit. 1995-01-10 07:32:52 +00:00
David Greenman
0d94caffca These changes embody the support of the fully coherent merged VM buffer cache,
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
1995-01-09 16:06:02 +00:00
Andreas Schulz
832f3afd12 Submitted by: Ben Jackson
just a missing newline in a kernel printf added.
1995-01-02 22:56:00 +00:00
David Greenman
eadf9e27cd These changes fix a couple of lingering VM problems:
1.	The pageout daemon used to block under certain
	circumstances, and we needed to add new functionality
	that would cause the pageout daemon to block more often.
	Now, the pageout daemon mostly just gets rid of pages
	and kills processes when the system is out of swap.
	The swapping, rss limiting and object cache trimming
	have been folded into a new daemon called "vmdaemon".
	This new daemon does things that need to be done for
	the VM system, but can block.  For example, if the
	vmdaemon blocks for memory, the pageout daemon
	can take care of it.  If the pageout daemon had
	blocked for memory, it was difficult to handle
	the situation correctly (and in some cases, was
	impossible).

2.	The collapse problem has now been entirely fixed.
	It now appears to be impossible to accumulate unnecessary
	vm objects.  The object collapsing now occurs when ref counts
	drop to one (where it is more likely to be more simple anyway
	because less pages would be out on disk.)  The original
	fixes were incomplete in that pathological circumstances
	could still be contrived to cause uncontrolled growth
	of swap.  Also, the old code still, under steady state
	conditions, used more swap space than necessary.  When
	using the new code, users will generally notice a
	significant decrease in swap space usage, and theoretically,
	the system should be leaving fewer unused pages around
	competing for memory.

Submitted by:	John Dyson
1994-11-25 07:58:29 +00:00
David Greenman
792216316f Don't ever try to kill off process 1 - even if we are out of swap space
and it's the candidate pig.
1994-11-17 06:24:25 +00:00
David Greenman
b0150bfc4b Set laundry flag when transitioning an inactive page from clean to dirty.
This fixes a performance bug where pages would sometimes not be paged
out when they could be.

Submitted by:	John Dyson
1994-11-14 02:57:40 +00:00
David Greenman
2fe6e4d71e Added support for starting the experimental "vmdaemon" system process.
Enabled via REL2_1.

Added support for doing object collapses "on the fly". Enabled via REL2_1a.

Improved object collapses so that they can happen in more cases. Improved
sensing of modified pages to fix an apparant race condition and improve
clustered pageout opportunities. Fixed an "oops" with not restarting page
scan after a potential block in vm_pageout_clean() (not doing this can result
in strange behavior in some cases).

Submitted by:	John Dyson & David Greenman
1994-11-06 05:07:53 +00:00
David Greenman
191ee5b300 #if 0'd out the object cache trimming code - there are multiple ways
that the pageout daemon can deadlock otherwise.

Submitted by:	John Dyson
1994-10-25 05:35:44 +00:00
David Greenman
e8fbe458e4 Fixed object cache trimming policy so it actually works.
Submitted by:	John Dyson
1994-10-23 21:03:09 +00:00
David Greenman
389918ee95 Adjusted reserved levels to fix a deadlock condition.
Submitted by:	John Dyson
1994-10-23 20:53:33 +00:00
David Greenman
5663e6de1c Various changes to allow operation without any swapspace configured. Note
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
1994-10-22 02:18:03 +00:00
David Greenman
a58d1fa15d Fix the remaining vmmeter counters. They all now work correctly. 1994-10-18 14:59:20 +00:00
David Greenman
976e77fc9c 1) Some of the counters in the vmmeter struct don't fit well into the Mach VM
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.
1994-10-15 13:33:09 +00:00
David Greenman
28e12d63f3 Fixed an object reference count problem that was caused by a call to
vm_object_lookup() being outside of some parens. The bug was introduced
via some recently added code.

Reviewed by:	John Dyson
1994-10-13 21:01:39 +00:00
Poul-Henning Kamp
05f0fdd26a Cosmetics: unused vars, ()'s, #include's &c &c to silence gcc.
Reviewed by:	davidg
1994-10-09 01:52:19 +00:00
Poul-Henning Kamp
4e39a515d4 Cosmetics. Unused vars and other warnings. 1994-10-07 07:23:04 +00:00
David Greenman
5cedf6806b Fixed minor bug caused by some missing parens that can result in slightly
reduced paging performance by missing a clustering opportunity. Found
by Poul-Henning Kamp with gcc -Wall.
1994-10-05 09:02:53 +00:00
David Greenman
edaaafdb0f Fixed bug related to proper sensing of page modification that we
inadvertantly introduced in pre-1.1.5. This could cause page modifications
to go unnoticed during certain extreme low memory/high paging rate conditions.

Submitted by:	John Dyson and David Greenman
1994-10-04 03:05:09 +00:00
David Greenman
11b224dca2 Fixed a bug I introduced when fixing the rss limit code. Changed swapout
policy to be a bit more selective about what processes get swapped out.

Reviewed by:	John Dyson
1994-09-12 15:06:14 +00:00
David Greenman
ed74321b1a Don't deactivate pages in 0-refcount objects. Added a couple of missing
paging stats. Fixed problem with free_reserved becoming depleted during
certain swap_pager operations.

Submitted by:	John Dyson, with a little help from me
1994-09-12 11:31:36 +00:00
David Greenman
a647a30954 Simple changes to paging algorithms...but boy do they make a difference.
FreeBSD's paging performance has never been better. Wow.

Submitted by:	John Dyson
1994-09-06 11:28:46 +00:00