(namely exec_map and phys_map) becuase:
- normal vmmpepl is fine for them.
- some of them are tightly sized. eg. size of exec_map on vax is just NCARGS.
should fix vax boot failure reported by Johnny Billquist on current-users@.
this means we can no longer look at the vnode size to determine how many
pages to request in a fault, which is good since for NFS the size can change
out from under us on the server anyway. there's also a new flag UBC_UNMAP
for ubc_release(), so that the file system code can make the decision about
whether to cache mappings for files being used as executables.
- allocate kva for vm_map_entry from the map itsself and
remove the static limit, MAX_KMAPENT.
- keep merged entries for later splitting to fix allocate-to-free problem.
PR/24039.
- decrement uvmexp.anonpages as it's no longer an anon page.
- null out anon->u.an_page as the anon no longer own the page.
uvm_anfree: add related assertions.
- Not enabled by default. Needs kernel option FFS_SNAPSHOT.
- Change parameters of ffs_blkfree.
- Let the copy-on-write functions return an error so spec_strategy
may fail if the copy-on-write fails.
- Change genfs_*lock*() to use vp->v_vnlock instead of &vp->v_lock.
- Add flag B_METAONLY to VOP_BALLOC to return indirect block buffer.
- Add a function ffs_checkfreefile needed for snapshot creation.
- Add special handling of snapshot files:
Snapshots may not be opened for writing and the attributes are read-only.
Use the mtime as the time this snapshot was taken.
Deny mtime updates for snapshot files.
- Add function transferlockers to transfer any waiting processes from
one lock to another.
- Add vfsop VFS_SNAPSHOT to take a snapshot and make it accessible through
a vnode.
- Add snapshot support to ls, fsck_ffs and dump.
Welcome to 2.0F.
Approved by: Jason R. Thorpe <thorpej@netbsd.org>
PG_RELEASED for anon pages. PR/23171 from Christian Limpach.
for details, see discussion filed in the PR database.
uvm_anon_release: a new function to free anon-owned PG_RELEASED page.
uvm_anfree: we can't wait for the page here because the caller might hold
amap lock. instead, just mark the page as PG_RELEASED.
who unbusy the page should check the PG_RELEASED.
uvm_aio_aiodone: uvm_anon_release() instead of uvm_page_unbusy()
if appropriate.
uvmfault_anonget: check PG_RELEASED.
to pool_init. Untouched pools are ones that either in arch-specific
code, or aren't initialiased during initial system startup.
Convert struct session, ucred and lockf to pools.
insert the replacement page into the same position
as the original page on the object memq so that
genfs_putpages (and lfs) won't be confused.
noted by Stephan Uphoff (PR/24328)
the latter is not a appropriate place to do so and it broke vfork.
- deactivate pmap before calling cpu_exit() to keep a balance of
pmap_activate/deactivate.
which is zero by default.
perform rbtree sanity checks only when it isn't zero
because the check is very heavy weight especially when
there're many entries.
in the case that there's no cached entries,
if kmem_map is already up, allocate a entry from it
so that we won't try to vm_map_lock recursively.
XXX assuming usage pattern of kmem_map.
and uncontrolled growth.
The key fix is from Dan Carasone, who noticed that buf_canfree() was
counting in _bytes_ but freeing in _buffers_, which caused the instant
drop to lowater observed by some users.
We now control the rate of growth; the probability of getting a new
allocation is inversely proportional to the current size of the
cache. This idea is from a long-ago conversation with Kirk McKusick
and, if memory serves, was used for the file-system cache in some
other BSD variant at some point in history.
With growth and shrinkage more or less dealt with, we return the
default maximum cache size to 15%. The default _minimum_ cache size
is raised from 1/16 of the maximum cache size to 1/8, since 1/16 was
chosen when the maximum size was 30% of memory.
Finally, after observing the behaviour of the pagedaemon and the
buffer cache drainer under pathological workloads (e.g. a benchmark
that steps through 75% of available memory backwards) I have moved
the call to buf_drain() to the beginning of the pagedaemon from the
end; if the pagedaemon bogs down, it still won't get run as often
as it should, but at least this way it will see the state of the
free count and free target _before_ the scan step does its thing.
- for in-kernel maps, disable map entry merging so that
unmap operations won't block. (workaround for PR/24039)
- for in-kernel maps, allocate kva for vm_map_entry from
the map itsself and eliminate MAX_KMAPENT and
uvm_map_entry_kmem_pool.
VOP_STRATEGY(bp) is replaced by one of two new functions:
- VOP_STRATEGY(vp, bp) Call the strategy routine of vp for bp.
- DEV_STRATEGY(bp) Call the d_strategy routine of bp->b_dev for bp.
DEV_STRATEGY(bp) is used only for block-to-block device situations.
This avoids problems with the kernel grovelling vmstat -u/-U when
using LOCKDEBUG, which changes the size of struct simplelock.
Replaced the original location of the simplelock with "int unused"
so that binary compatibility will be retained with old vmstat.
process context ('reaper').
From within the exiting process context:
* deactivate pmap and free vmspace while we can still block
* introduce MD cpu_lwp_free() - this cleans all MD-specific context (such
as FPU state), and is the last potentially blocking operation;
all of cpu_wait(), and most of cpu_exit(), is now folded into cpu_lwp_free()
* process is now immediatelly marked as zombie and made available for pickup
by parent; the remaining last lwp continues the exit as fully detached
* MI (rather than MD) code bumps uvmexp.swtch, cpu_exit() is now same
for both 'process' and 'lwp' exit
uvm_lwp_exit() is modified to never block; the u-area memory is now
always just linked to the list of available u-areas. Introduce (blocking)
uvm_uarea_drain(), which is called to release the excessive u-area memory;
this is called by parent within wait4(), or by pagedaemon on memory shortage.
uvm_uarea_free() is now private function within uvm_glue.c.
MD process/lwp exit code now always calls lwp_exit2() immediatelly after
switching away from the exiting lwp.
g/c now unneeded routines and variables, including the reaper kernel thread
virtual memory reservation and a private pool of memory pages -- by a scheme
based on memory pools.
This allows better utilization of memory because buffers can now be allocated
with a granularity finer than the system's native page size (useful for
filesystems with e.g. 1k or 2k fragment sizes). It also avoids fragmentation
of virtual to physical memory mappings (due to the former fixed virtual
address reservation) resulting in better utilization of MMU resources on some
platforms. Finally, the scheme is more flexible by allowing run-time decisions
on the amount of memory to be used for buffers.
On the other hand, the effectiveness of the LRU queue for buffer recycling
may be somewhat reduced compared to the traditional method since, due to the
nature of the pool based memory allocation, the actual least recently used
buffer may release its memory to a pool different from the one needed by a
newly allocated buffer. However, this effect will kick in only if the
system is under memory pressure.
uvm_km_valloc1(), and use it to express all of
uvm_km_valloc()
uvm_km_valloc_wait()
uvm_km_valloc_prefer()
uvm_km_valloc_prefer_wait()
uvm_km_valloc_align()
in terms of it by macro expansion.
Gone are the old kern_sysctl(), cpu_sysctl(), hw_sysctl(),
vfs_sysctl(), etc, routines, along with sysctl_int() et al. Now all
nodes are registered with the tree, and nodes can be added (or
removed) easily, and I/O to and from the tree is handled generically.
Since the nodes are registered with the tree, the mapping from name to
number (and back again) can now be discovered, instead of having to be
hard coded. Adding new nodes to the tree is likewise much simpler --
the new infrastructure handles almost all the work for simple types,
and just about anything else can be done with a small helper function.
All existing nodes are where they were before (numerically speaking),
so all existing consumers of sysctl information should notice no
difference.
PS - I'm sorry, but there's a distinct lack of documentation at the
moment. I'm working on sysctl(3/8/9) right now, and I promise to
watch out for buses.
copyin() or copyout().
uvm_useracc() tells us whether the mapping permissions allow access to
the desired part of an address space, and many callers assume that
this is the same as knowing whether an attempt to access that part of
the address space will succeed. however, access to user space can
fail for reasons other than insufficient permission, most notably that
paging in any non-resident data can fail due to i/o errors. most of
the callers of uvm_useracc() make the above incorrect assumption. the
rest are all misguided optimizations, which optimize for the case
where an operation will fail. we'd rather optimize for operations
succeeding, in which case we should just attempt the access and handle
failures due to insufficient permissions the same way we handle i/o
errors. since there appear to be no good uses of uvm_useracc(), we'll
just remove it.
(1) split the single list of pages allocated to a pool into three lists:
completely full, partially full, and completely empty.
there is no longer any need to traverse any list looking for a
certain type of page.
(2) replace the 8-element hash table for out-of-page page headers
with a splay tree.
these two changes (together with the recent enhancements to the wait code)
give us linear scaling for a fork+exit microbenchmark.
to improve scalability of operations on the map.
originally done by Niels Provos for OpenBSD.
tweaked for NetBSD by me with some advices from enami tsugutomo.
discussed on tech-kern@ and tech-perform@.
- after sleeping for memory, re-check if we have a page.
- put the allocated page to pageq to appease UVM_PAGE_TRKOWN.
- dequeue the page when doing ->K loan.
The case where l_stat == LSONPROC and l_cpu == curcpu cannot happen
because the pagedaemon is the LWP on curcpu and the pagedaemon is a
kernel thread and the code is only used by the pagedaemon.
See also updated patch in PR kern/23095, which I ment to checkin
originally.
uvm_swapout_threads will swapout LWPs which are running on another CPU:
- uvm_swapout_threads considers LWPs running on another CPU for swapout
if their l_swtime is high
- uvm_swapout_threads considers LWPs on the runqueue for swapout if their
l_swtime is high but these LWPs might be running by the time uvm_swapout
is called
symptoms of failure: panic in setrunqueue
fixes PR kern/23095
with the KVA of the newly-wired uarea.
This is useful on some architectures (e.g. xscale) where the uarea mapping
can be tweaked to use the mini-data cache instead of the main cache.
it may return space already in use as free space under some condition.
The symptom of the bug is that exec fails if stack is unlimited on
topdown VM kernel.
uvm_swap_free() being called with a zero slot; this might have been
the reason for crashes with sysvshm and heavy swapping.
(PR kern/22752 by Tom Spindler)
Confirmed by Chuck Silvers.
the `# swap page in use' and `# swap page only' counters. However, at the
time of swap device removal we can no longer figure out how many of the
bad swap pages are actually also `swap only' pages.
So, on swap I/O errors arrange things to not include the bad swap pages in
the `swpgonly' counter as follows: uvm_swap_markbad() decrements `swpgonly'
by the number of bad pages, and the various VM object deallocation routines
do not decrement `swpgonly' for swap slots marked as SWSLOT_BAD.
and make the stack and heap non-executable by default. the changes
fall into two basic catagories:
- pmap and trap-handler changes. these are all MD:
= alpha: we already track per-page execute permission with the (software)
PG_EXEC bit, so just have the trap handler pay attention to it.
= i386: use a new GDT segment for %cs for processes that have no
executable mappings above a certain threshold (currently the
bottom of the stack). track per-page execute permission with
the last unused PTE bit.
= powerpc/ibm4xx: just use the hardware exec bit.
= powerpc/oea: we already track per-page exec bits, but the hardware only
implements non-exec mappings at the segment level. so track the
number of executable mappings in each segment and turn on the no-exec
segment bit iff the count is 0. adjust the trap handler to deal.
= sparc (sun4m): fix our use of the hardware protection bits.
fix the trap handler to recognize text faults.
= sparc64: split the existing unified TSB into data and instruction TSBs,
and only load TTEs into the appropriate TSB(s) for the permissions.
fix the trap handler to check for execute permission.
= not yet implemented: amd64, hppa, sh5
- changes in all the emulations that put a signal trampoline on the stack.
instead, we now put the trampoline into a uvm_aobj and map that into
the process separately.
originally from openbsd, adapted for netbsd by me.
* Remove the "lwp *" argument that was added to vget(). Turns out
that nothing actually used it!
* Remove the "lwp *" arguments that were added to VFS_ROOT(), VFS_VGET(),
and VFS_FHTOVP(); all they did was pass it to vget() (which, as noted
above, didn't use it).
* Remove all of the "lwp *" arguments to internal functions that were added
just to appease the above.
be inserted into ktrace records. The general change has been to replace
"struct proc *" with "struct lwp *" in various function prototypes, pass
the lwp through and use l_proc to get the process pointer when needed.
Bump the kernel rev up to 1.6V
http://mail-index.netbsd.org/source-changes/2003/05/08/0068.html
There were some side-effects that I didn't anticipate, and fixing them
is proving to be more difficult than I thought, do just eject for now.
Maybe one day we can look at this again.
Fixes PR kern/21517.
space is advertised to UVM by making virtual_avail and virtual_end
first-class exported variables by UVM. Machine-dependent code is
responsible for initializing them before main() is called. Anything
that steals KVA must adjust these variables accordingly.
This reduces the number of instances of this info from 3 to 1, and
simplifies the pmap(9) interface by removing the pmap_virtual_space()
function call, and removing two arguments from pmap_steal_memory().
This also eliminates some kludges such as having to burn kernel_map
entries on space used by the kernel and stolen KVA.
This also eliminates use of VM_{MIN,MAX}_KERNEL_ADDRESS from MI code,
this giving MD code greater flexibility over the bounds of the managed
kernel virtual address space if a given port's specific platforms can
vary in this regard (this is especially true of the evb* ports).
first step towards per-device MAXPHYS, and has the beneficial side effect
of allowing clustering to MAXPHYS even on systems that need to run with
a reduced MAXBSIZE to get more metadata buffers.
* Remove DEFAULT_PAGE_SIZE. We don't use PAGE_SIZE the way Mach did.
* In uvm_setpagesize(), if we are called with uvmexp.pagesize == 0,
then assert that PAGE_SIZE != 0 (i.e. a constant), and set uvmexp.pagesize
accordingly.
* Provide defaults for MIN_PAGE_SIZE and MAX_PAGE_SIZE if not defined
by <machine/vmparam.h>. If PAGE_SIZE is not a constant, MIN_PAGE_SIZE
and MAX_PAGE_SIZE must be provided.
* If MIN_PAGE_SIZE and MAX_PAGE_SIZE are not equal (i.e. PAGE_SIZE may
not be a constant in all configurations), then ensure that PAGE_SIZE
and friends expand to variable references for LKMs.
* User allocates ZFOD region, but does not actually touch the buffer
to fault in the pages.
* In a loop, user writes this buffer to a network socket, triggering
sosend_loan().
* uvm_loan() calls uvm_loanzero() once for each page in the loaned
region (since the pages have not yet faulted in). This causes a
page to be allocated and zero'd. The result is the kernel spends
a lot of time allocating and zero'ing pages.
This fixes creates a special object which owns a single zero'd page.
This single zero'd page is used to satisfy all loans of non-resident
ZFOD mappings.
Thanks to Allen Briggs for discovering the problem and for providing
an initial patch.
previous entry. (not if the current entry starts at the end of the new
space; that case doesn't take into account if the new space had a specified
alignment).
means that the dynamic linker gets mapped in at the top of available
user virtual memory (typically just below the stack), shared libraries
get mapped downwards from that point, and calls to mmap() that don't
specify a preferred address will get mapped in below those.
This means that the heap and the mmap()ed allocations will grow
towards each other, allowing one or the other to grow larger than
before. Previously, the heap was limited to MAXDSIZ by the placement
of the dynamic linker (and the process's rlimits) and the space
available to mmap was hobbled by this reservation.
This is currently only enabled via an *option* for the i386 platform
(though other platforms are expected to follow). Add "options
USE_TOPDOWN_VM" to your kernel config file, rerun config, and rebuild
your kernel to take advantage of this.
Note that the pmap_prefer() interface has not yet been modified to
play nicely with this, so those platforms require a bit more work
(most notably the sparc) before they can use this new memory
arrangement.
This change also introduces a VM_DEFAULT_ADDRESS() macro that picks
the appropriate default address based on the size of the allocation or
the size of the process's text segment accordingly. Several drivers
and the SYSV SHM address assignment were changed to use this instead
of each one picking their own "default".
(there are still some details to work out) but expect that to go
away soon. To support these basic changes (creation of lfs_putpages,
lfs_gop_write, mods to lfs_balloc) several other changes were made, to
wit:
* Create a writer daemon kernel thread whose purpose is to handle page
writes for the pagedaemon, but which also takes over some of the
functions of lfs_check(). This thread is started the first time an
LFS is mounted.
* Add a "flags" parameter to GOP_SIZE. Current values are
GOP_SIZE_READ, meaning that the call should return the size of the
in-core version of the file, and GOP_SIZE_WRITE, meaning that it
should return the on-disk size. One of GOP_SIZE_READ or
GOP_SIZE_WRITE must be specified.
* Instead of using malloc(...M_WAITOK) for everything, reserve enough
resources to get by and use malloc(...M_NOWAIT), using the reserves if
necessary. Use the pool subsystem for structures small enough that
this is feasible. This also obsoletes LFS_THROTTLE.
And a few that are not strictly necessary:
* Moves the LFS inode extensions off onto a separately allocated
structure; getting closer to LFS as an LKM. "Welcome to 1.6O."
* Unified GOP_ALLOC between FFS and LFS.
* Update LFS copyright headers to correct values.
* Actually cast to unsigned in lfs_shellsort, like the comment says.
* Keep track of which segments were empty before the previous
checkpoint; any segments that pass two checkpoints both dirty and
empty can be summarily cleaned. Do this. Right now lfs_segclean
still works, but this should be turned into an effectless
compatibility syscall.
we read-lock the map and call uvm_map_lookup_entry() instead of simply
walking from the header to the next and to the next, etc.
Dumping from sparsely populated amaps could cause faults that would
result in amaps being split, which (in turn) resulted in the core
dumping routines dumping some regions of memory twice. This makes the
core file too large, the headers not match, gdb not work properly,
and so on.
Addresses PR 19260.
malloc types into a structure, a pointer to which is passed around,
instead of an int constant. Allow the limit to be adjusted when the
malloc type is defined, or with a function call, as suggested by
Jonathan Stone.
request may contain PGO_DONTCARE and nfs_getpages may unbusy them on error.
Fix is provided in PR#20028 by YAMAMOTO Takashi. (and same one is approved
by chuq while ago in private mail). It was my fault to forget to commit.
allocated ppref data to zero in the case of an amap that has empty
space at the front.
Don't set anything in the ppref array if "len" is zero.
Many thanks to Sami Kantoluoto for providing gdb access to a machine
that would reliably crash with problems related to the above, and to
Stephan Thesing for corroborating that the patch properly addressed
the problem.
Note that the ar_pageoff (and related variables) types must be changed
soon. The use of "int" here is not theoretically sufficient.
to sleep. Define UVM_KMF_NOWAIT in terms of UVM_FLAG_NOWAIT.
From Manuel Bouyer. Fixes a problem where any mapping with
read protection was created in a "nowait" context, causing
spurious failures.
uvm_map(). Change uvm_map() to honnor UVM_KMF_NOWAIT. For this, change
amap_extend() to take a flags parameter instead of just boolean for
direction, and introduce AMAP_EXTEND_FORWARDS and AMAP_EXTEND_NOWAIT flags
(AMAP_EXTEND_BACKWARDS is still defined as 0x0, to keep the code easier to
read).
Add a flag parameter to uvm_mapent_alloc().
This solves a problem a pool_get(PR_NOWAIT) could trigger a pool_get(PR_WAITOK)
in uvm_mapent_alloc().
Thanks to Chuck Silvers, enami tsugutomo, Andrew Brown and Jason R Thorpe
for feedback.
