the page table page's wired count rather than its hold count to contain
the reference count. My rationale for this change is based on several
factors:
1. The machine-independent and pmap layers used the same hold count field
in subtly different ways. The machine-independent layer uses the hold
count to implement a form of ephemeral wiring that is used by pipes,
physio, etc. In other words, subsystems where we wish to temporarily
block a page from being swapped out while it is mapped into the kernel's
address space. Such pages are never removed from the page queues.
Instead, the page daemon recognizes a non-zero hold count to mean "hands
off this page." In contrast, page table pages are never in the page
queues; they are wired from birth to death. The hold count was being
used as a kind of reference count, specifically, the number of valid
page table entries within the page. Not surprisingly, these two
different uses imply different synchronization rules: in the machine-
independent layer access to the hold count requires the page queues
lock; whereas in the pmap layer the pmap lock is required. Thus,
continued use by the pmap layer of vm_page_unhold(), which asserts that
the page queues lock is held, made no sense.
2. _pmap_unwire_pte_hold() was too forgiving in its handling of the wired
count. An unexpected wired count on a page table page was ignored and
the underlying page leaked.
3. In a word, microoptimization. Using the wired count exclusively, rather
than a combination of the wired and hold counts, makes the code slightly
smaller and faster.
Reviewed by: tegge@
UMA_ZONE_NOFREE to guarantee type stability, so proc_fini() should
never be called. Move an assertion from proc_fini() to proc_dtor()
and garbage-collect the rest of the unreachable code. I have retained
vm_proc_dispose(), since I consider its disuse a bug.
too much kernel copying, but it is not the right way to do it, and it is
in the way for straightening out the buffer cache.
The right way is to pass the VM page array down through the struct
bio to the disk device driver and DMA directly in to/out off the
physical memory. Once the VM/buf thing is sorted out it is next on
the list.
Retire most of vnode method. ffs_getpages(). It is not clear if what is
left shouldn't be in the default implementation which we now fall back to.
Retire specfs_getpages() as well, as it has no users now.
Completely remove the remaining EFI includes and add our own (type)
definitions instead. While here, abstract more of the internals by
providing interface functions.
Analogous to the drive level, give each volume and plex a worker thread
that picks up and processes incoming and completed BIOs.
This should fix the data corruption issues that have come up a few
weeks ago and improve performance, especially of RAID5 plexes.
The volume level needs a little work, though.
- Add "Hardware Support" section and move device driver-related
items there.
- Move "Multimedia Support" and "Network Interface Support" into
the "Hardware Support" section as sub-sections.
- Move Netgraph-related items to "Network Protocols".
For translators: many items are moved but the contents
are not changed.
to 4.0 and RELENG_3), the BTX mini-kernel used paging rather than flat
mode and clients were limited to a virtual address space of 16 megabytes.
Because of this limitation, boot2 silently masked all physical addresses
in any binaries it loaded so that they were always loaded into the first
16 Meg. Since BTX no longer has this limitation (and hasn't for a long
time), remove the masking from boot2. This allows boot2 to load kernels
larger than about 12 to 14 meg (12 for non-PAE, 14 for PAE).
Submitted by: Sergey Lyubka devnull at uptsoft dot com
MFC after: 1 month
