Commit Graph

28 Commits

Author SHA1 Message Date
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
aa2cabb958 1) Converted v_vmdata to v_object.
2) Removed unnecessary vm_object_lookup()/pager_cache(object, TRUE) pairs
   after vnode_pager_alloc() calls - the object is already guaranteed to be
   persistent.
3) Removed some gratuitous casts.
1995-06-28 12:01:13 +00:00
David Greenman
9879652657 Fixed VOP_LINK argument order botch. 1995-06-28 07:06:55 +00:00
Rodney W. Grimes
9b2e535452 Remove trailing whitespace. 1995-05-30 08:16:23 +00:00
Rodney W. Grimes
b2b795f07c Fix -Wformat warnings from LINT kernel. 1995-05-11 19:26:53 +00:00
John Dyson
e5f751a9b2 Changes to get rid of ufslk2 hangs when doing read/write to/from
mmap regions that are in the same file as the read/write.
1995-04-24 05:13:28 +00:00
David Greenman
5291a9a0ac Make vegetarian and animal rights people happy and use 0xdeadc0de instead
of 0xdeadbeef as the 'spare' value.
1995-04-16 11:25:47 +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
Bruce Evans
3aa12267a5 Add and move declarations to fix all of the warnings from `gcc -Wimplicit'
(except in netccitt, netiso and netns) that I didn't notice when I fixed
"all" such warnings before.
1995-03-28 07:58:53 +00:00
David Greenman
f57459b632 Removed third arg (vmio) to allocbuf() that was added with the original
merged cache changes, and figure it out based on the B_VMIO buffer flag.
Fixes a problem where delayed write VMIO buffers would sometimes get
recopied into kernel-alloced memory.

Submitted by:	John Dyson
1995-03-26 23:29:13 +00:00
David Greenman
edf8a81561 Removed redundant newlines that were in some panic strings. 1995-03-19 14:29:26 +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
403ef252fa Removed obsolete vtrace() remnants. 1995-03-04 03:24:45 +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
Justin T. Gibbs
1a451e33ef LFS stability patches. There is still a problem with directory update
ordering that can prove fatal during large batches of deletes, but this
is much better than it was.  I probably won't be putting much more time
into this until Seltzer releases her new version of LFS which has
fragment support.  This should be availible just before USENIX.
1995-01-04 23:46:34 +00:00
Justin T. Gibbs
471e5fa096 John Dyson's patches (and a few from me too) to LFS to use a different
buffering scheme and make it more in tune with FreeBSD's vfs_bio
implementation.  The filesystem seems fairly stable, but I wouldn't recommend
it to anyone not willing to experience problems.  This is very green code and
has the limitation that YOU CAN ONLY HAVE ONE LFS PARTITION MOUNTED AT A TIME.

What LFS is good for:

	Non fsynced writes	FASTER THAN FFS
	Large deletions		Increadibly fast

Reads are a little bit slower than FFS right now, but that is a factor of
how under optimized this code is.  LFS should in theory perform at least as
well as FFS under fsync (iozone) type loads, and this is what I'm currently
working on.

Reviewed by:	Justin Gibbs
Submitted by:	John Dyson
Obtained from:
1994-11-17 01:30:53 +00:00
Bruce Evans
36633bf49d Undo a previous change. <sys/disklabel.h> was broken, not these files. 1994-11-14 13:22:52 +00:00
Jordan K. Hubbard
94a92413cd From: fredriks@mcs.com (Lars Fredriksen)
...
It turns out that these files do not include <sys/dkbad.h> before
<sys/disklabel.h>.
Submitted by:	fredriks
1994-10-28 12:42:05 +00:00
Poul-Henning Kamp
c1d9efcbb9 Cosmetics. make gcc less noisy. Still some way to go here. 1994-10-10 01:04:55 +00:00
Garrett Wollman
c9b1d6048d More loadable VFS changes:
- Make a number of filesystems work again when they are statically compiled
  (blush)

- FIFOs are no longer optional; ``options FIFO'' removed from distributed
  config files.
1994-09-22 19:38:41 +00:00
Garrett Wollman
c901836c14 Implemented loadable VFS modules, and made most existing filesystems
loadable.  (NFS is a notable exception.)
1994-09-21 03:47:43 +00:00
David Greenman
1cdeb653a8 "bogus" fixes from 1.1.5 to work around some cache coherency problems. 1994-08-29 06:09:15 +00:00
Paul Richards
3301cc3c0a Made idempotent
Reviewed by:
Submitted by:
1994-08-21 07:19:45 +00:00
David Greenman
e0e9c42112 Implemented filesystem clean bit via:
machdep.c:
	Changed printf's a little and call vfs_unmountall() if the sync was
	successful.

cd9660_vfsops.c, ffs_vfsops.c, nfs_vfsops.c, lfs_vfsops.c:
	Allow dismount of root FS. It is now disallowed at a higher level.

vfs_conf.c:
	Removed unused rootfs global.

vfs_subr.c:
	Added new routines vfs_unmountall and vfs_unmountroot. Filesystems
	are now dismounted if the machine is properly rebooted.

ffs_vfsops.c:
	Toggle clean bit at the appropriate places. Print warning if an
	unclean FS is mounted.

ffs_vfsops.c, lfs_vfsops.c:
	Fix bug in selecting proper flags for VOP_CLOSE().

vfs_syscalls.c:
	Disallow dismounting root FS via umount syscall.
1994-08-20 16:03:26 +00:00
David Greenman
7b42c960f8 1) cleaned up after Garrett - fixed more redundant declarations, changed
use of timeout_t -> timeout_func_t in aha1542 and aha1742 drivers.
2) fix a bug in the portalfs that was uncovered by better prototyping -
   specifically, the time must be converted from timeval to timespec
   before storing in va_atime.
3) fixed/added some miscellaneous prototypes
1994-08-20 03:49:02 +00:00
David Greenman
3c4dd3568f Added $Id$ 1994-08-02 07:55:43 +00:00
Rodney W. Grimes
26f9a76710 The big 4.4BSD Lite to FreeBSD 2.0.0 (Development) patch.
Reviewed by:	Rodney W. Grimes
Submitted by:	John Dyson and David Greenman
1994-05-25 09:21:21 +00:00
Rodney W. Grimes
df8bae1de4 BSD 4.4 Lite Kernel Sources 1994-05-24 10:09:53 +00:00