Commit Graph

35 Commits

Author SHA1 Message Date
David Greenman
628641f8a6 Converted mountlist to a CIRCLEQ.
Partially obtained from: 4.4BSD-Lite2
1995-08-11 11:31:18 +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
e0dca2b939 Improve negative usecount diagnostic a little. 1995-07-08 04:10:32 +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
Bruce Evans
6acceb40dc Pass the correct nonblocking flag to VOP_CLOSE() in vclean().
VOP_CLOSE() takes `F' (file) flags, not `IO' flags.  At least that's
what close() passes.  I previously fixed ttylclose() to check
FNONBLOCK instead of IO_NDELAY.  This broke the call from vclean()
and cleaning of ptys sometimes deadlocked.
1995-06-27 21:29:08 +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
15f1b09648 Increased ratio of allowed vnodes on freelist to 1/4th of the total. This
is more representative of worst case situations of 4 files/directory. (If
that last sentence doesn't make any sense, I'm not surprised. It's rather
compilcated how this all fits together....).
This should fix a problem that Ed Hudson has been complaining about where
directories with lots of symlinks could cause excessive disk I/O.
1995-05-12 04:24:53 +00:00
David Greenman
1a477b0c27 Changed #ifdef around printlockedvnodes() from DEBUG to DDB. 1995-04-16 11:33:33 +00:00
David Greenman
213fd1b6e8 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
call 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 06:02:46 +00:00
David Greenman
b946193056 Fixed vinvalbuf() to work like NFS wants it to. The previous code wouldn't
flush pages in the vm object if V_SAVE was true.
1995-03-21 01:13:16 +00:00
David Greenman
62b71ed629 Don't gain/lose a reference to the object when yanking its pages in
vinvalbuf()...it will cause vnode locking problems in vm_object_terminate,
and isn't necessary anyway.
1995-03-20 10:19:09 +00:00
David Greenman
ff769afc81 Don't attempt to sync pages in the V_SAVE case of vinvalbuf; doing so can
lead to a deadlock. Just let the VM system deal with it.
1995-03-20 02:08:24 +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
3d2a8cf3d9 Added a comment. 1995-03-11 22:29:07 +00:00
David Greenman
f8a0b2dd88 Reorganized an if() expression for efficiency. 1995-03-10 21:18:24 +00:00
Poul-Henning Kamp
fbd6e6c9ef Clean up and improve the namecache.
1. We always keep one 16th of the vnodes on the freelist, so that the
namecache doesn't get trashed.  It used to be that it wasn't a problem, but
the only vnodes getting released these days are directories and things which
Clean up and improve the namecache.

1. We always keep one 16th of the vnodes on the freelist, so that the
namecache doesn't get trashed.  It used to be that it wasn't a problem, but
the only vnodes getting released these days are directories and things which
gets forced out of the VM/cache.  The latter is not numerous enough to keep
the pool of vnodes needed for the namecache sufficiently big.

2. Purge invalid entries in the namecache as soon as we notice them.  This
avoids a stale entry pushing out a valid entry on the LRU list.

3. Speed up the lookup in the namecache by avoid a special case branch.

4. Make the cache purge routines do the thing they're supposed to, and in
a decently efficient manner.

5. Make the size of the namecache follow the number of vnodes, so that we
can always point to all the vnodes we have in core.

6. Readability has gone way up.

7. Added a "options NCH_STATISTICS" feature that will gather more
detailed statistics on the performance of the namecache.

Reviewed by:    davidg

(cvs is dumping core on me :-(  )
1995-03-09 20:27:04 +00:00
David Greenman
acc835fd3f Put VAGE vnodes at the head of the free list. 1995-03-07 18:59:45 +00:00
David Greenman
7500ed1d63 Backed out previous change. I forgot (for about the fourth time) that
v_rdev is a #define which is dereferenced through v_specinfo->si_rdev,
and that isn't initialized until later in checkalias().
1995-02-27 10:15:38 +00:00
David Greenman
f9ceb7c7b5 Initialize v_rdev in getnewvnode() - it appears that some filesystems
may not properly initialize this field in all cases, and this would
result in very anti-social behavior (overwriting on some other random
device/location).

Submitted by:	John Dyson
1995-02-27 06:50:08 +00:00
David Greenman
a3a8bb29d2 vfs_cluster.c:
Various more tweaks from John Dyson to improve read ahead calculations.

vfs_subr.c:
Only wakeup if numoutput is 0 in vwakeup().

Submitted by:	John Dyson
1995-02-22 09:39:22 +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
David Greenman
602d2b481a Protect vnode buffer chain manipulation with splbio to prevent list
corruption..
1994-12-23 04:52:55 +00:00
David Greenman
824789192c Use tsleep() rather than sleep so that 'ps' is more informative about
the wait.
1994-10-06 21:07:04 +00:00
David Greenman
8e58bf6875 Stuff object into v_vmdata rather than pager. Not important which at
the moment, but will be in the future. Other changes mostly cosmetic,
but are made for future VMIO considerations.

Submitted by:	John Dyson
1994-10-05 09:48:45 +00:00
Poul-Henning Kamp
797f2d22f0 All of this is cosmetic. prototypes, #includes, printfs and so on. Makes
GCC a lot more silent.
1994-10-02 17:35:40 +00:00
Poul-Henning Kamp
bb56ec4a05 While in the real world, I had a bad case of being swapped out for a lot of
cycles.  While waiting there I added a lot of the extra ()'s I have, (I have
never used LISP to any extent).  So I compiled the kernel with -Wall and
shut up a lot of "suggest you add ()'s", removed a bunch of unused var's
and added a couple of declarations here and there.  Having a lap-top is
highly recommended.  My kernel still runs, yell at me if you kernel breaks.
1994-09-25 19:34:02 +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
David Greenman
e0c0215442 Initialized v_writecount. 1994-08-24 04:06:39 +00:00
David Greenman
4f5a3fef1a print "BUSY" instead of error number if filesystem was busy during
vfs_unmountall() - this is the most common case. If it was a different
error, then print the error number.
1994-08-22 17:05:00 +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
Garrett Wollman
f23b4c91c4 Fix up some sloppy coding practices:
- 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.
1994-08-18 22:36:09 +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