clearing the page's PGA_REFERENCED flag. Since we are typically
manipulating the page's act_count field when we are clearing its
PGA_REFERENCED flag, the page lock is already held everywhere that we clear
the PGA_REFERENCED flag. So, in fact, this revision only changes some
comments and an assertion. Nonetheless, it will enable later changes to
object locking in the pageout code.
Introduce vm_page_assert_locked(), which completely hides the implementation
details of the page lock from the caller, and use it in
vm_page_aflag_clear(). (The existing vm_page_lock_assert() could not be
used in vm_page_aflag_clear().) Over the coming weeks, I expect that we'll
either eliminate or replace the various uses of vm_page_lock_assert() with
vm_page_assert_locked().
Reviewed by: attilio
Sponsored by: EMC / Isilon Storage Division
lock instead of the object lock, there is no reason for vm_page_activate()
to assert that the object is locked for either read or write access.
(The "VPO_UNMANAGED" flag never changes after page allocation.)
Sponsored by: EMC / Isilon Storage Division
reason to inline the implementation of vm_page_lock_assert() in the
!KLD_MODULES case. Use the same implementation for both KLD_MODULES and
!KLD_MODULES.
Reviewed by: kib
change. Retest the ref_count and return from the function to not
execute the further code which assumes that ref_count == 1 if it is
not. Also, do not leak vnode lock if other thread cleared OBJ_TMPFS
flag meantime.
Reported by: bdrewery
Tested by: bdrewery, pho
Sponsored by: The FreeBSD Foundation
It can now be accessed with a write lock on the object containing it OR
with a read lock on the object containing it along with the swhash_mtx.
o Remove some duplicate assertions for swap_pager_freespace() and
swap_pager_unswapped() but keep the object locking references for
documentation.
Sponsored by: EMC / Isilon storage division
Reviewed by: alc
o Relax locking assertions for pmap_enter_object() and add them also
to architectures that currently don't have any
o Introduce VM_OBJECT_LOCK_DOWNGRADE() which is basically a downgrade
operation on the per-object rwlock
o Use all the mechanisms above to make vm_map_pmap_enter() to work
mostl of the times only with readlocks.
Sponsored by: EMC / Isilon storage division
Reviewed by: alc
a vm page, denoted either by an address of the struct vm_page, or, if
the '/p' modifier is specified, by a physical address of the
corresponding frame.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
tree is used to maintain the object's collection of resident pages,
vm_page_lookup() no longer needs an exclusive lock.
Reviewed by: attilio
Sponsored by: EMC / Isilon Storage Division
freelist.
o Split the pool of free pages queues really by domain and not rely on
definition of VM_RAW_NFREELIST.
o For MAXMEMDOM > 1, wrap the RR allocation logic into a specific
function that is called when calculating the allocation domain.
The RR counter is kept, currently, per-thread.
In the future it is expected that such function evolves in a real
policy decision referee, based on specific informations retrieved by
per-thread and per-vm_object attributes.
o Add the concept of "probed domains" under the form of vm_ndomains.
It is responsibility for every architecture willing to support multiple
memory domains to correctly probe vm_ndomains along with mem_affinity
segments attributes. Those two values are supposed to remain always
consistent.
Please also note that vm_ndomains and td_dom_rr_idx are both int
because segments already store domains as int. Ideally u_int would
have much more sense. Probabilly this should be cleaned up in the
future.
o Apply RR domain selection also to vm_phys_zero_pages_idle().
Sponsored by: EMC / Isilon storage division
Partly obtained from: jeff
Reviewed by: alc
Tested by: jeff
vm_page_insert() so that (1) vm_radix_lookup_le() is never called while the
free page queues lock is held and (2) vm_radix_lookup_le() is called at most
once. This change reduces the average time that the free page queues lock
is held by vm_page_alloc() as well as vm_page_alloc()'s average overall
running time.
Sponsored by: EMC / Isilon Storage Division
functions, reverse the numbering scheme for the levels. The highest
numbered level in the tree now appears near the root instead of the leaves.
Sponsored by: EMC / Isilon Storage Division
order to match the MAXCPU concept. The change should also be useful
for consolidation and consistency.
Sponsored by: EMC / Isilon storage division
Obtained from: jeff
Reviewed by: alc
change the way that these functions ascend the tree when the search for a
matching leaf fails at an interior node. Rather than returning to the root
of the tree and repeating the lookup with an updated key, maintain a stack
of interior nodes that were visited during the descent and use that stack
to resume the lookup at the closest ancestor that might have a matching
descendant.
Sponsored by: EMC / Isilon Storage Division
Reviewed by: attilio
Tested by: pho
- vm_phys_alloc_freelist_pages() can be called by vm_page_alloc_freelist()
to allocate a page from a specific freelist. In the NUMA case it did not
properly map the public VM_FREELIST_* constants to the correct backing
freelists, nor did it try all NUMA domains for allocations from
VM_FREELIST_DEFAULT.
- vm_phys_alloc_pages() did not pin the thread and each call to
vm_phys_alloc_freelist_pages() fetched the current domain to choose
which freelist to use. If a thread migrated domains during the loop
in vm_phys_alloc_pages() it could skip one of the freelists. If the
other freelists were out of memory then it is possible that
vm_phys_alloc_pages() would fail to allocate a page even though pages
were available resulting in a panic in vm_page_alloc().
Reviewed by: alc
MFC after: 1 week
vnode v_object to avoid double-buffering. Use the same object both as
the backing store for tmpfs node and as the v_object.
Besides reducing memory use up to 2x times for situation of mapping
files from tmpfs, it also makes tmpfs read and write operations copy
twice bytes less.
VM subsystem was already slightly adapted to tolerate OBJT_SWAP object
as v_object. Now the vm_object_deallocate() is modified to not
reinstantiate OBJ_ONEMAPPING flag and help the VFS to correctly handle
VV_TEXT flag on the last dereference of the tmpfs backing object.
Reviewed by: alc
Tested by: pho, bf
MFC after: 1 month
v_object of non OBJT_VNODE type.
For vm_object_page_clean(), simply do not assert that object type must
be OBJT_VNODE, and add a comment explaining how the check for
OBJ_MIGHTBEDIRTY prevents the rest of function from operating on such
objects.
For vm_mmap_vnode(), if the object type is not OBJT_VNODE, require it
to be for swap pager (or default), handle the bypass filesystems, and
correctly acquire the object reference in this case.
Reviewed by: alc
Tested by: pho, bf
MFC after: 1 week
to vnode_pager_setsize(), is either OBJT_VNODE, or, if vnode was
already reclaimed, OBJT_DEAD. Note that the later is only possible
due to some filesystems, in particular, nfsiods from nfs clients, call
vnode_pager_setsize() with unlocked vnode.
More, if the object is terminated, do not perform the resizing
operation.
Reviewed by: alc
Tested by: pho, bf
MFC after: 1 week
the number of interior nodes, we have previously created a level zero
interior node at the root of every non-empty trie, even when that node is
not strictly necessary, i.e., it has only one child. This change is the
second (and final) step in eliminating those unnecessary level zero interior
nodes. Specifically, it updates the deletion and insertion functions so
that they do not require a level zero interior node at the root of the trie.
For a "buildworld" workload, this change results in a 16.8% reduction in the
number of interior nodes allocated and a similar reduction in the average
execution time for lookup functions. For example, the average execution
time for a call to vm_radix_lookup_ge() is reduced by 22.9%.
Reviewed by: attilio, jeff (an earlier version)
Sponsored by: EMC / Isilon Storage Division
the number of interior nodes, we always create a level zero interior node at
the root of every non-empty trie, even when that node is not strictly
necessary, i.e., it has only one child. This change is the first step in
eliminating those unnecessary level zero interior nodes. Specifically, it
updates all of the lookup functions so that they do not require a level zero
interior node at the root.
Reviewed by: attilio, jeff (an earlier version)
Sponsored by: EMC / Isilon Storage Division
for us_freecount.
This grows uma_slab_head on 32-bit arches, but growth isn't
significant. Taking kmem zones as example, only the 32 byte
zone is affected, ipers is reduced from 113 to 112.
In collaboration with: kib
with the MAP_ENTRY_VN_WRITECNT flag:
- Move the assertion that verifies the state of the v_writecount and
vnp.writecount, under the block where the object is locked.
- Check that the object type is OBJT_VNODE before asserting.
Reported by: avg
Reviewed by: alc
MFC after: 1 week
per-page lock rather than vm_object lock, without any further overhead.
Make the formal switch.
Sponsored by: EMC / Isilon storage division
Reviewed by: alc
Tested by: pho
These zones have slab size == sizeof(struct pcpu), but request from VM
enough pages to fit (uk_slabsize * mp_ncpus). An item allocated from such
zone would have a separate twin for each CPU in the system, and these twins
are at a distance of sizeof(struct pcpu) from each other. This magic value
of distance would allow us to make some optimizations later.
To address private item from a CPU simple arithmetics should be used:
item = (type *)((char *)base + sizeof(struct pcpu) * curcpu)
These arithmetics are available as zpcpu_get() macro in pcpu.h.
To introduce non-page size slabs a new field had been added to uma_keg
uk_slabsize. This shifted some frequently used fields of uma_keg to the
fourth cache line on amd64. To mitigate this pessimization, uma_keg fields
were a bit rearranged and least frequently used uk_name and uk_link moved
down to the fourth cache line. All other fields, that are dereferenced
frequently fit into first three cache lines.
Sponsored by: Nginx, Inc.
arrange for all of the fields to start at a short offset from the
beginning of the structure.
Eliminate unnecessary masking of VM_RADIX_FLAGS from the root pointer in
vm_radix_getroot().
Sponsored by: EMC / Isilon Storage Division
- Don't insert BKGRDMARKER bufs into the splay or dirty/clean buf lists.
No consumers need to find them there and it complicates the tree.
These flags are all FFS specific and could be moved out of the buf
cache.
- Use pbgetvp() and pbrelvp() to associate the background and journal
bufs with the vp. Not only is this much cheaper it makes more sense
for these transient bufs.
- Fix the assertions in pbget* and pbrel*. It's not safe to check list
pointers which were never initialized. Use the BX flags instead. We
also check B_PAGING in reassignbuf() so this should cover all cases.
Discussed with: kib, mckusick, attilio
Sponsored by: EMC / Isilon Storage Division
vm_radix_topage(). This transformation eliminates some unnecessary
conditional branches from the inner loops of vm_radix_insert(),
vm_radix_lookup{,_ge,_le}(), and vm_radix_remove().
Simplify the control flow of vm_radix_lookup_{ge,le}().
Reviewed by: attilio (an earlier version)
Tested by: pho
Sponsored by: EMC / Isilon Storage Division
before the vnode is vput() in vm_mmap_vnode(). Error return means
that there is no use reference on the vnode from the vm object
reference, and failing to restore v_writecount breaks the invariant
that v_writecount is less or equal to the usecount.
The situation observed when nfs client returns ESTALE for
VOP_GETATTR() after the open.
In collaboration with: pho
MFC after: 1 week
using vm_radix_node_page() == NULL, the compiler is able to generate one
less conditional branch when vm_radix_isleaf() is used. More use cases
involving the inner loops of vm_radix_insert(), vm_radix_lookup{,_ge,_le}(),
and vm_radix_remove() will follow.
Reviewed by: attilio
Sponsored by: EMC / Isilon Storage Division
that could never be reached in vm_radix_insert(). (If the pointer being
checked by the panic call were ever NULL, the immmediately preceding loop
would have already crashed on a NULL pointer dereference.)
Reviewed by: attilio (an earlier version)
Sponsored by: EMC / Isilon Storage Division
