Commit Graph

125 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
28a3c3c9a6 Killed the "probably_never" ifdef'd code. 1995-06-28 04:51:06 +00:00
Rodney W. Grimes
9b2e535452 Remove trailing whitespace. 1995-05-30 08:16:23 +00:00
David Greenman
243e5a88d5 Fixed panic that resulted from mmaping files in kernfs and procfs. A
regular user could panic the machine with a simple "tail /proc/curproc/mem"
command. The problem was twofold: both kernfs and procfs didn't fill in
the mnt_stat statfs struct (which would later lead to an integer divide
fault in the vnode pager), and kernfs bogusly paniced if a bmap was
attempted.

Reviewed by:	John Dyson
1995-05-25 01:35:24 +00:00
Rodney W. Grimes
b2b795f07c Fix -Wformat warnings from LINT kernel. 1995-05-11 19:26:53 +00:00
David Greenman
d7e03b7a8b For P_SUGID processes, we must also change ownership of the mem file
to root so that group kmem can still get to it. *SIGH*
1995-04-15 03:20:31 +00:00
David Greenman
5232af2cf1 Retain group kmem readability for P_SUGID processes. 1995-04-15 02:50:13 +00:00
David Greenman
f62e09f22e Made /proc/n/mem file group kmem and group readable. Needed to fix ps so
that it doesn't need to be setuid root.
1995-04-15 02:30:17 +00:00
Garrett Wollman
bbf3a56610 Add four more filesystem flags:
VFCF_NETWORK (this FS goes over the net)
	VFCF_READONLY (read-write mounts do not make any sense)
	VFCF_SYNTHETIC (data in this FS is not real)
	VFCF_LOOPBACK (this FS aliases something else)

cd9660 is readonly; nullfs, umapfs, and union are loopback; NFS is netowkr;
procfs, kernfs, and fdesc are synthetic.
1995-03-16 20:23:48 +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
59a9ecebb5 Make sure process isn't swapped when messing with it.
Added missing newline to log() call.
1995-02-20 15:53:33 +00:00
David Greenman
efc68ce10f Fixed bmap run-length brokeness.
Use bmap run-length extension when doing clustered paging.

Submitted by:	John Dyson
1995-02-03 06:46:28 +00:00
David Greenman
f81dd52383 Initialize map start hint to vm_map_find()...not doing so will cause it
to fail if the random thing on the stack happens to be too large.

Submitted by:	David Jones <dej@qpoint.torfree.net>
1995-01-05 03:59:38 +00:00
Andrey A. Chernov
16e544e7a1 Fix problem when attached process detached
Submitted by: Gary Jennejohn
1994-12-31 12:26:50 +00:00
David Greenman
1b4bb67169 Fixed bug I just introduced that would have allowed a user to clobber
his kernel stack.
1994-10-18 04:40:41 +00:00
David Greenman
2d8f106204 Allow upages to be paged in/accessed.
Submitted by:	John Dyson
1994-10-18 04:26:53 +00:00
Poul-Henning Kamp
3a773ad0b5 Cosmetics. reduce the noise from gcc -Wall. 1994-10-10 07:55:48 +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
0f85a55965 1) Added "." and ".." entries.
2) Fixed directory size to return something reasonable.
3) Disabled "file" until the code is completed.
4) Corrected directory link counts.
1994-09-24 17:01:05 +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
Bruce Evans
0ad076d56a Supply prototypes for some functions that were implicitly declared and
fix the resulting warnings.
1994-09-15 19:47:47 +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