Commit Graph

194 Commits

Author SHA1 Message Date
Jeff Roberson
670d17b5c0 Remove references to vm_zone.h and switch over to the new uma API. 2002-03-20 04:02:59 +00:00
Alfred Perlstein
11caded34f Remove __P. 2002-03-19 22:20:14 +00:00
Jeff Roberson
8355f576a9 This is the first part of the new kernel memory allocator. This replaces
malloc(9) and vm_zone with a slab like allocator.

Reviewed by:	arch@
2002-03-19 09:11:49 +00:00
Brian Feldman
25adb370be Back out the modification of vm_map locks from lockmgr to sx locks. The
best path forward now is likely to change the lockmgr locks to simple
sleep mutexes, then see if any extra contention it generates is greater
than removed overhead of managing local locking state information,
cost of extra calls into lockmgr, etc.

Additionally, making the vm_map lock a mutex and respecting it properly
will put us much closer to not needing Giant magic in vm.
2002-03-18 15:08:09 +00:00
Brian Feldman
0e0af8ecda Rename SI_SUB_MUTEX to SI_SUB_MTX_POOL to make the name at all accurate.
While doing this, move it earlier in the sysinit boot process so that the
VM system can use it.

After that, the system is now able to use sx locks instead of lockmgr
locks in the VM system.  To accomplish this, some of the more
questionable uses of the locks (such as testing whether they are
owned or not, as well as allowing shared+exclusive recursion) are
removed, and simpler logic throughout is used so locks should also be
easier to understand.

This has been tested on my laptop for months, and has not shown any
problems on SMP systems, either, so appears quite safe.  One more
user of lockmgr down, many more to go :)
2002-03-13 23:48:08 +00:00
Eivind Eklund
a128794977 - Remove a number of extra newlines that do not belong here according to
style(9)
- Minor space adjustment in cases where we have "( ", " )", if(), return(),
  while(), for(), etc.
- Add /* SYMBOL */ after a few #endifs.

Reviewed by:	alc
2002-03-10 21:52:48 +00:00
Mike Silbersack
7f3a40933b Fix a horribly suboptimal algorithm in the vm_daemon.
In order to determine what to page out, the vm_daemon checks
reference bits on all pages belonging to all processes.  Unfortunately,
the algorithm used reacted badly with shared pages; each shared page
would be checked once per process sharing it; this caused an O(N^2)
growth of tlb invalidations.  The algorithm has been changed so that
each page will be checked only 16 times.

Prior to this change, a fork/sleepbomb of 1300 processes could cause
the vm_daemon to take over 60 seconds to complete, effectively
freezing the system for that time period.  With this change
in place, the vm_daemon completes in less than a second.  Any system
with hundreds of processes sharing pages should benefit from this change.

Note that the vm_daemon is only run when the system is under extreme
memory pressure.  It is likely that many people with loaded systems saw
no symptoms of this problem until they reached the point where swapping
began.

Special thanks go to dillon, peter, and Chuck Cranor, who helped me
get up to speed with vm internals.

PR:		33542, 20393
Reviewed by:	dillon
MFC after:	1 week
2002-02-27 18:03:02 +00:00
Mike Silbersack
ef6020d187 Changes to make the OOM killer much more effective:
- Allow the OOM killer to target processes currently locked in
  memory.  These very often are the ones doing the memory hogging.
- Drop the wakeup priority of processes currently sleeping while
  waiting for their page fault to complete.  In order for the OOM
  killer to work well, the killed process and other system processes
  waiting on memory must be allowed to wakeup first.

Reviewed by:	dillon
MFC after:	1 week
2002-02-19 18:34:02 +00:00
Matthew Dillon
027df6bdd7 GC P_BUFEXHAUST leftovers, we've had a new mechanism to avoid buffer
cache lockups for over a year now.

MFC after:		0 days
2002-01-31 18:39:44 +00:00
Matthew Dillon
23b590188f Fix a BUF_TIMELOCK race against BUF_LOCK and fix a deadlock in vget()
against VM_WAIT in the pageout code.  Both fixes involve adjusting
the lockmgr's timeout capability so locks obtained with timeouts do not
interfere with locks obtained without a timeout.

Hopefully MFC: before the 4.5 release
2001-12-20 22:42:27 +00:00
Matthew Dillon
57601bcb5d Syntax cleanup and documentation, no operational changes.
MFC after:	1 day
2001-10-21 06:12:06 +00:00
Tor Egge
30105b9ec4 Don't remove all mappings of a swapped out process if the vm map contained
wired entries.  vm_fault_unwire() depends on the mapping being intact.

Reviewed by:	dillon
2001-10-14 20:51:14 +00:00
Julian Elischer
b40ce4165d KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after:    ha ha ha ha
2001-09-12 08:38:13 +00:00
Matthew Dillon
6d03d577a5 Reorg vm_page.c into vm_page.c, vm_pageq.c, and vm_contig.c (for contigmalloc).
Also removed some spl's and added some VM mutexes, but they are not actually
used yet, so this commit does not really make any operational changes
to the system.

vm_page.c relates to vm_page_t manipulation, including high level deactivation,
activation, etc...  vm_pageq.c relates to finding free pages and aquiring
exclusive access to a page queue (exclusivity part not yet implemented).
And the world still builds... :-)
2001-07-04 23:27:09 +00:00
Matthew Dillon
54d9214595 whitespace / register cleanup 2001-07-04 19:00:13 +00:00
Matthew Dillon
0cddd8f023 With Alfred's permission, remove vm_mtx in favor of a fine-grained approach
(this commit is just the first stage).  Also add various GIANT_ macros to
formalize the removal of Giant, making it easy to test in a more piecemeal
fashion. These macros will allow us to test fine-grained locks to a degree
before removing Giant, and also after, and to remove Giant in a piecemeal
fashion via sysctl's on those subsystems which the authors believe can
operate without Giant.
2001-07-04 16:20:28 +00:00
John Baldwin
ad6c5bbede Don't lock around swap_pager_swap_init() that is only called once during
the pagedaemon's startup code since it calls malloc which results in lock
order reversals.
2001-06-20 23:34:06 +00:00
John Baldwin
69a78d4666 Put the scheduler, vmdaemon, and pagedaemon kthreads back under Giant for
now.  The proc locking isn't actually safe yet and won't be until the proc
locking is finished.
2001-06-20 00:48:20 +00:00
Matthew Dillon
ff2b5645b5 Two fixes to the out-of-swap process termination code. First, start killing
processes a little earlier to avoid a deadlock.  Second, when calculating
the 'largest process' do not just count RSS.  Instead count the RSS + SWAP
used by the process.  Without this the code tended to kill small
inconsequential processes like, oh, sshd, rather then one of the many
'eatmem 200MB' I run on a whim :-).  This fix has been extensively tested on
-stable and somewhat tested on -current and will be MFCd in a few days.

Shamed into fixing this by: ps
2001-06-09 18:06:58 +00:00
John Baldwin
3614c6fcbb - Add in several asserts of vm_mtx.
- Assert Giant in vm_pageout_scan() for the vnode hacking that it does.
- Don't hold vm_mtx around vget() or vput().
- Lock Giant when calling vm_pageout_scan() from the pagedaemon.  Also,
  lock curproc while setting the P_BUFEXHAUST flag.
- For now we still hold Giant for all of the vm_daemon.  When process
  limits are locked we will be only need Giant for swapout_procs().
2001-05-23 22:48:28 +00:00
Alfred Perlstein
2395531439 Introduce a global lock for the vm subsystem (vm_mtx).
vm_mtx does not recurse and is required for most low level
vm operations.

faults can not be taken without holding Giant.

Memory subsystems can now call the base page allocators safely.

Almost all atomic ops were removed as they are covered under the
vm mutex.

Alpha and ia64 now need to catch up to i386's trap handlers.

FFS and NFS have been tested, other filesystems will need minor
changes (grabbing the vm lock when twiddling page properties).

Reviewed (partially) by: jake, jhb
2001-05-19 01:28:09 +00:00
John Baldwin
1c58e4e550 During the code to pick a process to kill when memory is exhausted, keep
the process in question locked as soon as we find it and determine it to
be eligible until we actually kill it.  To avoid deadlock, we don't block
on the process lock but skip any process that is already locked during our
search.
2001-05-17 22:49:03 +00:00
Mark Murray
fb919e4d5a Undo part of the tangle of having sys/lock.h and sys/mutex.h included in
other "system" header files.

Also help the deprecation of lockmgr.h by making it a sub-include of
sys/lock.h and removing sys/lockmgr.h form kernel .c files.

Sort sys/*.h includes where possible in affected files.

OK'ed by:	bde (with reservations)
2001-05-01 08:13:21 +00:00
John Baldwin
1005a129e5 Convert the allproc and proctree locks from lockmgr locks to sx locks. 2001-03-28 11:52:56 +00:00
Bosko Milekic
9ed346bab0 Change and clean the mutex lock interface.
mtx_enter(lock, type) becomes:

mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks)
mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized)

similarily, for releasing a lock, we now have:

mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN.
We change the caller interface for the two different types of locks
because the semantics are entirely different for each case, and this
makes it explicitly clear and, at the same time, it rids us of the
extra `type' argument.

The enter->lock and exit->unlock change has been made with the idea
that we're "locking data" and not "entering locked code" in mind.

Further, remove all additional "flags" previously passed to the
lock acquire/release routines with the exception of two:

MTX_QUIET and MTX_NOSWITCH

The functionality of these flags is preserved and they can be passed
to the lock/unlock routines by calling the corresponding wrappers:

mtx_{lock, unlock}_flags(lock, flag(s)) and
mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN
locks, respectively.

Re-inline some lock acq/rel code; in the sleep lock case, we only
inline the _obtain_lock()s in order to ensure that the inlined code
fits into a cache line. In the spin lock case, we inline recursion and
actually only perform a function call if we need to spin. This change
has been made with the idea that we generally tend to avoid spin locks
and that also the spin locks that we do have and are heavily used
(i.e. sched_lock) do recurse, and therefore in an effort to reduce
function call overhead for some architectures (such as alpha), we
inline recursion for this case.

Create a new malloc type for the witness code and retire from using
the M_DEV type. The new type is called M_WITNESS and is only declared
if WITNESS is enabled.

Begin cleaning up some machdep/mutex.h code - specifically updated the
"optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN
and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently
need those.

Finally, caught up to the interface changes in all sys code.

Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Poul-Henning Kamp
fc2ffbe604 Mechanical change to use <sys/queue.h> macro API instead of
fondling implementation details.

Created with: sed(1)
Reviewed by: md5(1)
2001-02-04 13:13:25 +00:00
John Baldwin
8606d88043 - Catch up to proc flag changes.
- Minimal proc locking.
- Use queue macros.
2001-01-24 11:28:36 +00:00
Matthew Dillon
2b6b0df712 This implements a better launder limiting solution. There was a solution
in 4.2-REL which I ripped out in -stable and -current when implementing the
low-memory handling solution.  However, maxlaunder turns out to be the saving
grace in certain very heavily loaded systems (e.g. newsreader box).  The new
algorithm limits the number of pages laundered in the first pageout daemon
pass.  If that is not sufficient then suceessive will be run without any
limit.

Write I/O is now pipelined using two sysctls, vfs.lorunningspace and
vfs.hirunningspace.  This prevents excessive buffered writes in the
disk queues which cause long (multi-second) delays for reads.  It leads
to more stable (less jerky) and generally faster I/O streaming to disk
by allowing required read ops (e.g. for indirect blocks and such) to occur
without interrupting the write stream, amoung other things.

NOTE: eventually, filesystem write I/O pipelining needs to be done on a
per-device basis.  At the moment it is globalized.
2000-12-26 19:41:38 +00:00
Seigo Tanimura
21cd6e6232 - If swap metadata does not fit into the KVM, reduce the number of
struct swblock entries by dividing the number of the entries by 2
until the swap metadata fits.

- Reject swapon(2) upon failure of swap_zone allocation.

This is just a temporary fix. Better solutions include:
(suggested by:	dillon)

o reserving swap in SWAP_META_PAGES chunks, and
o swapping the swblock structures themselves.

Reviewed by:	alfred, dillon
2000-12-13 10:01:00 +00:00
Jake Burkholder
c0c2557090 - Change the allproc_lock to use a macro, ALLPROC_LOCK(how), instead
of explicit calls to lockmgr.  Also provides macros for the flags
  pased to specify shared, exclusive or release which map to the
  lockmgr flags.  This is so that the use of lockmgr can be easily
  replaced with optimized reader-writer locks.
- Add some locking that I missed the first time.
2000-12-13 00:17:05 +00:00
Matthew Dillon
02fa91d35e Be less conservative with a recently added KASSERT. Certain edge
cases with file fragments and read-write mmap's can lead to a situation
    where a VM page has odd dirty bits, e.g. 0xFC - due to being dirtied by
    an mmap and only the fragment (representing a non-page-aligned end of
    file) synced via a filesystem buffer.  A correct solution that
    guarentees consistent m->dirty for the file EOF case is being
    worked on.  In the mean time we can't be so conservative in the
    KASSERT.
2000-12-11 07:52:47 +00:00
John Baldwin
c5a44a6af6 Protect p_stat with sched_lock. 2000-12-02 06:09:44 +00:00
Jake Burkholder
553629ebc9 Protect the following with a lockmgr lock:
allproc
	zombproc
	pidhashtbl
	proc.p_list
	proc.p_hash
	nextpid

Reviewed by:	jhb
Obtained from:	BSD/OS and netbsd
2000-11-22 07:42:04 +00:00
Matthew Dillon
936524aa02 Implement a low-memory deadlock solution.
Removed most of the hacks that were trying to deal with low-memory
    situations prior to now.

    The new code is based on the concept that I/O must be able to function in
    a low memory situation.  All major modules related to I/O (except
    networking) have been adjusted to allow allocation out of the system
    reserve memory pool.  These modules now detect a low memory situation but
    rather then block they instead continue to operate, then return resources
    to the memory pool instead of cache them or leave them wired.

    Code has been added to stall in a low-memory situation prior to a vnode
    being locked.

    Thus situations where a process blocks in a low-memory condition while
    holding a locked vnode have been reduced to near nothing.  Not only will
    I/O continue to operate, but many prior deadlock conditions simply no
    longer exist.

Implement a number of VFS/BIO fixes

	(found by Ian): in biodone(), bogus-page replacement code, the loop
        was not properly incrementing loop variables prior to a continue
        statement.  We do not believe this code can be hit anyway but we
        aren't taking any chances.  We'll turn the whole section into a
        panic (as it already is in brelse()) after the release is rolled.

	In biodone(), the foff calculation was incorrectly
        clamped to the iosize, causing the wrong foff to be calculated
        for pages in the case of an I/O error or biodone() called without
        initiating I/O.  The problem always caused a panic before.  Now it
        doesn't.  The problem is mainly an issue with NFS.

	Fixed casts for ~PAGE_MASK.  This code worked properly before only
        because the calculations use signed arithmatic.  Better to properly
        extend PAGE_MASK first before inverting it for the 64 bit masking
        op.

	In brelse(), the bogus_page fixup code was improperly throwing
        away the original contents of 'm' when it did the j-loop to
        fix the bogus pages.  The result was that it would potentially
        invalidate parts of the *WRONG* page(!), leading to corruption.

	There may still be cases where a background bitmap write is
        being duplicated, causing potential corruption.  We have identified
        a potentially serious bug related to this but the fix is still TBD.
        So instead this patch contains a KASSERT to detect the problem
  	and panic the machine rather then continue to corrupt the filesystem.
	The problem does not occur very often..  it is very hard to
	reproduce, and it may or may not be the cause of the corruption
	people have reported.

Review by: (VFS/BIO: mckusick, Ian Dowse <iedowse@maths.tcd.ie>)
Testing by: (VM/Deadlock) Paul Saab <ps@yahoo-inc.com>
2000-11-18 23:06:26 +00:00
Jason Evans
0384fff8c5 Major update to the way synchronization is done in the kernel. Highlights
include:

* Mutual exclusion is used instead of spl*().  See mutex(9).  (Note: The
  alpha port is still in transition and currently uses both.)

* Per-CPU idle processes.

* Interrupts are run in their own separate kernel threads and can be
  preempted (i386 only).

Partially contributed by:	BSDi (BSD/OS)
Submissions by (at least):	cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
Kirk McKusick
f2a2857bb3 Add snapshots to the fast filesystem. Most of the changes support
the gating of system calls that cause modifications to the underlying
filesystem. The gating can be enabled by any filesystem that needs
to consistently suspend operations by adding the vop_stdgetwritemount
to their set of vnops. Once gating is enabled, the function
vfs_write_suspend stops all new write operations to a filesystem,
allows any filesystem modifying system calls already in progress
to complete, then sync's the filesystem to disk and returns. The
function vfs_write_resume allows the suspended write operations to
begin again. Gating is not added by default for all filesystems as
for SMP systems it adds two extra locks to such critical kernel
paths as the write system call. Thus, gating should only be added
as needed.

Details on the use and current status of snapshots in FFS can be
found in /sys/ufs/ffs/README.snapshot so for brevity and timelyness
is not included here. Unless and until you create a snapshot file,
these changes should have no effect on your system (famous last words).
2000-07-11 22:07:57 +00:00
Matthew Dillon
8b03c8ed5e This is a cleanup patch to Peter's new OBJT_PHYS VM object type
and sysv shared memory support for it.  It implements a new
    PG_UNMANAGED flag that has slightly different characteristics
    from PG_FICTICIOUS.

    A new sysctl, kern.ipc.shm_use_phys has been added to enable the
    use of physically-backed sysv shared memory rather then swap-backed.
    Physically backed shm segments are not tracked with PV entries,
    allowing programs which use a large shm segment as a rendezvous
    point to operate without eating an insane amount of KVM in the
    PV entry management.  Read: Oracle.

    Peter's OBJT_PHYS object will also allow us to eventually implement
    page-table sharing and/or 4MB physical page support for such segments.
    We're half way there.
2000-05-29 22:40:54 +00:00
Matthew Dillon
883f3caa13 Fix bug in vm_pageout_page_stats() that always resulted in a full
scan of the active queue.  This fix is not expected to have any
    noticeable impact on performance.

Noticed by: Rik van Riel <riel@conectiva.com.br>
2000-05-29 02:31:55 +00:00
Peter Wemm
249645144d Checkpoint of a new physical memory backed object type, that does not
have pv_entries.  This is intended for very special circumstances,
eg: a certain database that has a 1GB shm segment mapped into 300
processes.  That would consume 2GB of kvm just to hold the pv_entries
alone.  This would not be used on systems unless the physical ram was
available, as it's not pageable.

This is a work-in-progress, but is a useful and functional checkpoint.
Matt has got some more fixes for it that will be committed soon.

Reviewed by:	dillon
2000-05-21 13:41:29 +00:00
Peter Wemm
0385347c1a Implement an optimization of the VM<->pmap API. Pass vm_page_t's directly
to various pmap_*() functions instead of looking up the physical address
and passing that.  In many cases, the first thing the pmap code was doing
was going to a lot of trouble to get back the original vm_page_t, or
it's shadow pv_table entry.

Inspired by: John Dyson's 1998 patches.

Also:
Eliminate pv_table as a seperate thing and build it into a machine
dependent part of vm_page_t.  This eliminates having a seperate set of
structions that shadow each other in a 1:1 fashion that we often went to
a lot of trouble to translate from one to the other. (see above)
This happens to save 4 bytes of physical memory for each page in the
system.  (8 bytes on the Alpha).

Eliminate the use of the phys_avail[] array to determine if a page is
managed (ie: it has pv_entries etc).  Store this information in a flag.
Things like device_pager set it because they create vm_page_t's on the
fly that do not have pv_entries.  This makes it easier to "unmanage" a
page of physical memory (this will be taken advantage of in subsequent
commits).

Add a function to add a new page to the freelist.  This could be used
for reclaiming the previously wasted pages left over from preloaded
loader(8) files.

Reviewed by:	dillon
2000-05-21 12:50:18 +00:00
Matthew Dillon
25db2c5417 Add necessary spl protection for swapper. The problem was located by
Alfred while testing his SPLASSERT stuff.   This is not a complete fix,
    more protections are probably needed.
2000-03-27 21:33:32 +00:00
Philippe Charnier
5929bcfaba Revert spelling mistake I made in the previous commit
Requested by: Alan and Bruce
2000-03-27 20:41:17 +00:00
Philippe Charnier
956f31353c Spelling 2000-03-26 15:20:23 +00:00
Eivind Eklund
6bdfe06ad9 Lock reporting and assertion changes.
* lockstatus() and VOP_ISLOCKED() gets a new process argument and a new
  return value: LK_EXCLOTHER, when the lock is held exclusively by another
  process.
* The ASSERT_VOP_(UN)LOCKED family is extended to use what this gives them
* Extend the vnode_if.src format to allow more exact specification than
  locked/unlocked.

This commit should not do any semantic changes unless you are using
DEBUG_VFS_LOCKS.

Discussed with:	grog, mch, peter, phk
Reviewed by:	peter
1999-12-11 16:13:02 +00:00
Alan Cox
be72f78813 The core of this patch is to vm/vm_page.h. The effects are two-fold: (1) to
eliminate an extra (useless) level of indirection in half of the page
queue accesses and (2) to use a single name for each queue throughout,
instead of, e.g., "vm_page_queue_active" in some places and
"vm_page_queues[PQ_ACTIVE]" in others.

Reviewed by:	dillon
1999-10-30 07:37:14 +00:00
Poul-Henning Kamp
923502ff91 useracc() the prequel:
Merge the contents (less some trivial bordering the silly comments)
of <vm/vm_prot.h> and <vm/vm_inherit.h> into <vm/vm.h>.  This puts
the #defines for the vm_inherit_t and vm_prot_t types next to their
typedefs.

This paves the road for the commit to follow shortly: change
useracc() to use VM_PROT_{READ|WRITE} rather than B_{READ|WRITE}
as argument.
1999-10-29 18:09:36 +00:00
Matthew Dillon
90ecac61c0 Reviewed by: Alan Cox <alc@cs.rice.edu>, David Greenman <dg@root.com>
Replace various VM related page count calculations strewn over the
    VM code with inlines to aid in readability and to reduce fragility
    in the code where modules depend on the same test being performed
    to properly sleep and wakeup.

    Split out a portion of the page deactivation code into an inline
    in vm_page.c to support vm_page_dontneed().

    add vm_page_dontneed(), which handles the madvise MADV_DONTNEED
    feature in a related commit coming up for vm_map.c/vm_object.c.  This
    code prevents degenerate cases where an essentially active page may
    be rotated through a subset of the paging lists, resulting in premature
    disposal.
1999-09-17 04:56:40 +00:00
Peter Wemm
c3aac50f28 $Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00
Alan Cox
aeea9b3695 Remove two unused variable declarations. 1999-08-22 00:01:46 +00:00
Alan Cox
bfbacbd93f vm_pageout_clean:
Remove dead code.

Submitted by:	dillon
1999-08-17 00:07:35 +00:00