History log of /haiku/headers/private/kernel/vm/vm_types.h
Revision Date Author Comments
# 73ad2473 05-Nov-2013 Pawel Dziepak <pdziepak@quarnos.org>

Remove remaining unnecessary 'volatile' qualifiers


# 90c6930e 04-Nov-2011 Michael Lotz <mmlr@mlotz.ch>

Add VM page allocation tracking similar to what happens in the slab already.
Introduces "page_allocation_infos" and "page_allocations_per_caller" KDL
commands.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@43190 a95241bf-73f2-0310-859d-f6bbb57e9c96


# b9447668 10-Jul-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Moved the vm_page initialization from vm_page.cpp:vm_page_init() to the new
vm_page::Init().
* Made vm_page::wired_count private and added accessor methods.
* Added VMCache::fWiredPagesCount (the number of wired pages the cache
contains) and accessor methods.
* Made more use of vm_page::IsMapped().
* vm_copy_on_write_area(): Added vm_page_reservation* parameter that can be
used to request a special handling for wired pages. If given the wired pages
are replaced by copies and the original pages are moved to the upper cache.
* vm_copy_area():
- We don't need to do any wired ranges handling, if the source area is a
B_SHARED_AREA, since we don't touch the area's mappings in this case.
- We no longer wait for wired ranges of the concerned areas to disappear.
Instead we use the new vm_copy_on_write_area() feature and just let it
copy the wired pages. This fixes #6288, an issue introduced with the use
of user mutexes in libroot: When executing multiple concurrent fork()s all
but the first one would wait on the fork mutex, which (being a user mutex)
would wire a page that the vm_copy_area() of the first fork() would wait
for.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37460 a95241bf-73f2-0310-859d-f6bbb57e9c96


# a8ad734f 14-Jun-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Introduced structures {virtual,physical}_address_restrictions, which specify
restrictions for virtual/physical addresses.
* vm_page_allocate_page_run():
- Fixed conversion of base/limit to array indexes. sPhysicalPageOffset was not
taken into account.
- Takes a physical_address_restrictions instead of base/limit and also
supports alignment and boundary restrictions, now.
* map_backing_store(), VM[User,Kernel]AddressSpace::InsertArea()/
ReserveAddressRange() take a virtual_address_restrictions parameter, now. They
also support an alignment independent from the range size.
* create_area_etc(), vm_create_anonymous_area(): Take
{virtual,physical}_address_restrictions parameters, now.
* Removed no longer needed B_PHYSICAL_BASE_ADDRESS.
* DMAResources:
- Fixed potential overflows of uint32 when initializing from device node
attributes.
- Fixed bounce buffer creation TODOs: By using create_area_etc() with the
new restrictions parameters we can directly support physical high address,
boundary, and alignment.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37131 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 147133b7 25-May-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* First run through the kernel's private parts to use phys_{addr,size}_t
where appropriate.
* Typedef'ed page_num_t to phys_addr_t and used it in more places in
vm_page.{h,cpp}.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36937 a95241bf-73f2-0310-859d-f6bbb57e9c96


# fe0963a8 18-Mar-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

Added commands to the page access debugging panic()s.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35904 a95241bf-73f2-0310-859d-f6bbb57e9c96


# bd7645a1 20-Feb-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Made vm_page::state private and added accessor methods.
* Added kernel tracing for page state transitions.



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35538 a95241bf-73f2-0310-859d-f6bbb57e9c96


# d36b9aef 19-Feb-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

Added vm_page::IsMapped() for convenience.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35531 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 40bb9481 03-Feb-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Removed useless return parameter from vm_remove_all_page_mappings().
* Added vm_clear_page_mapping_accessed_flags() and
vm_remove_all_page_mappings_if_unaccessed(), which combine the functionality
of vm_test_map_activation(), vm_clear_map_flags(), and
vm_remove_all_page_mappings(), thus saving lots of calls to translation map
methods. The backend is the new method
VMTranslationMap::ClearAccessedAndModified().
* Started to make use of the cached page queue and changed the meaning of the
other non-free queues slightly:
- Active queue: Contains mapped pages that have been used recently.
- Inactive queue: Contains mapped pages that have not been used recently. Also
contains unmapped temporary pages.
- Modified queue: Contains unmapped modified pages.
- Cached queue: Contains unmapped unmodified pages (LRU sorted).
Unless we're actually low on memory and actively do paging, modified and
cached queues only contain non-temporary pages. Cached pages are considered
quasi free. They still belong to a cache, but since they are unmodified and
unmapped, they can be freed immediately. And this is what
vm_page_[try_]reserve_pages() do now when there are no more actually free
pages at hand. Essentially this means that pages storing cached file data,
unless mmap()ped, no longer are considered used and don't contribute to page
pressure. Paging will not happen as long there are enough free + cached pages
available.
* Reimplemented the page daemon. It no longer scans all pages, but instead works
the page queues. As long as the free pages situation is harmless, it only
iterates through the active queue and deactivates pages that have not been
used recently. When paging occurs it additionally scans the inactive queue and
frees pages that have not been used recently.
* Changed the page reservation/allocation interface:
vm_page_[try_]reserve_pages(), vm_page_unreserve_pages(), and
vm_page_allocate_page() now take a vm_page_reservation structure pointer.
The reservation functions initialize the structure -- currently consisting
only of a count member for the number of still reserved pages.
vm_page_allocate_page() decrements the count and vm_page_unreserve_pages()
unreserves the remaining pages (if any). Advantages are that reservation/
unreservation mismatches cannot occur anymore, that vm_page_allocate_page()
can verify that the caller has indeed a reserved page left, and that there's
no unnecessary pressure on the free page pool anymore. The only disadvantage
is that the vm_page_reservation object needs to be passed around a bit.
* Reworked the page reservation implementation:
- Got rid of sSystemReservedPages and sPageDeficit. Instead
sUnreservedFreePages now actually contains the number of free pages that
have not yet been reserved (it cannot become negative anymore) and the new
sUnsatisfiedPageReservations contains the number of pages that are still
needed for reservation.
- Threads waiting for reservations do now add themselves to a waiter queue,
which is ordered by descending priority (VM priority and thread priority).
High priority waiters are served first when pages become available.
Fixes #5328.
* cache_prefetch_vnode(): Would reserve one less page than allocated later, if
the size wasn't page aligned.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35393 a95241bf-73f2-0310-859d-f6bbb57e9c96


# e65c4002 29-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Replaced the vm_page_allocate_page*() "pageState" parameter by a more
general "flags" parameter. It encodes the target state of the page -- so
that the page isn't unnecessarily put in the wrong page queue first -- a
flag whether the page should be cleared, and one to indicate whether the
page should be marked busy.
* Added page state PAGE_STATE_CACHED. Not used yet.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35333 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 72382fa6 29-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Removed the page state PAGE_STATE_BUSY and instead introduced a vm_page::busy
flag. The obvious advantage is that one can still see what state a page is in
and even move it between states while being marked busy.
* Removed the vm_page::is_dummy flag. Instead we mark marker pages busy, which
in all cases has the same effect. Introduced a vm_page_is_dummy() that can
still check whether a given page is a dummy page.
* vm_page_unreserve_pages(): Before adding to the system reserve make sure
sUnreservedFreePages is non-negative. Otherwise we'd make nonexisting pages
available for allocation. steal_pages() still has the same problem and it
can't be solved that easily.
* map_page(): No longer changes the page state/mark the page unbusy. That's the
caller's responsibility.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35331 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 6379e53e 19-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

vm_page no longer points directly to its containing cache, but rather to a
VMCacheRef object which points to the cache. This allows to optimize
VMCache::MoveAllPages(), since it no longer needs to iterate over all pages
to adjust their cache pointer. It can simple swap the cache refs of the two
caches instead.

Reduces the total -j8 Haiku image build time only marginally. The kernel time
drops almost 10%, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35155 a95241bf-73f2-0310-859d-f6bbb57e9c96


# f082f7f0 15-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Added vm_page::accessed flag. Works analogously to vm_page::modified.
* Reorganized the code for [un]mapping pages:
- Added new VMTranslationMap::Unmap{Area,Page[s]}() which essentially do what
vm_unmap_page[s]() did before, just in the architecture specific code, which
allows for specific optimizations. UnmapArea() is for the special case that
the complete area is unmapped. Particularly in case the address space is
deleted, some work can be saved. Several TODOs could be slain.
- Since they are only used within vm.cpp vm_map_page() and vm_unmap_page[s]()
are now static and have lost their prefix (and the "preserveModified"
parameter).
* Added VMTranslationMap::Protect{Page,Area}(). They are just inline wrappers
for Protect().
* X86VMTranslationMap::Protect(): Make sure not to accidentally clear the
accessed/dirty flags.
* X86VMTranslationMap::Unmap()/Protect(): Make page table skipping actually
work. It was only skipping to the next page.
* Adjusted the PPC code to at least compile.

No measurable effect for the -j8 Haiku image build time, though the kernel time
drops minimally.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35089 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 3b8c056d 11-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

Should have been part of r35023: Introduction of the vm_page::modified flag.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35024 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 451ca8b4 11-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

PAGE_TYPE_GUARD was unused and for the other two types a simple one bit flag
suffices. Therefore replaced vm_page::type by vm_page::is_dummy.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35013 a95241bf-73f2-0310-859d-f6bbb57e9c96


# d7455de2 11-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

allocate_page_run(): Use temporary lists to store the pages we're allocating.
This makes appending the pages to the active queue more efficient and we
don't need the vm_page::is_cleared bit anymore.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35011 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 3cd20943 06-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Added new debug feature (DEBUG_PAGE_ACCESS) to detect invalid concurrent
access to a vm_page. It is basically an atomically accessed thread ID field
in the vm_page structure, which is explicitly set by macros marking the
critical sections. As a first positive effect I had to review quite a bit of
code and found several issues.
* Added several TODOs and comments. Some harmless ones, but also a few
troublesome ones in vm.cpp regarding page unmapping.
* file_cache: PrecacheIO::Prepare()/read_into_cache: Removed superfluous
vm_page_allocate_page() return value checks. It cannot fail anymore.
* Removed the heavily contended "pages" lock. We use different policies now:
- sModifiedTemporaryPages is accessed atomically.
- sPageDeficitLock and sFreePageCondition are protected by a new mutex.
- The page queues have individual locks (mutexes).
- Renamed set_page_state_nolock() to set_page_state(). Unless the caller says
otherwise, it does now lock the affected pages queues itself. Also changed
the return value to void -- we panic() anyway.
* set_page_state(): Add free/clear pages to the beginning of their respective
queues as this is more cache-friendly.
* Pages with the states PAGE_STATE_WIRED or PAGE_STATE_UNUSED are no longer
in any queue. They were in the "active" queue, but there's no good reason
to have them there. In case we decide to let the page daemon work the queues
(like FreeBSD) they would just be in the way.
* Pulled the common part of vm_page_allocate_page_run[_no_base]() into a helper
function. Also fixed a bug I introduced previously: The functions must not
vm_page_unreserve_pages() on success, since they remove the pages from the
free/clear queue without decrementing sUnreservedFreePages.
* vm_page_set_state(): Changed return type to void. The function cannot really
fail and no-one was checking it anyway.
* vm_page_free(), vm_page_set_state(): Added assertion: The page must not be
free/clear before. This is implied by the policy that no-one is allowed to
access free/clear pages without holding the respective queue's lock, which is
not the case at this point. This found the bug fixed in r34912.
* vm_page_requeue(): Added general assertions. panic() when requeuing of
free/clear pages is requested. Same reason as above.
* vm_clone_area(), B_FULL_LOCK case: Don't map busy pages. The implementation is
still not correct, though.

My usual -j8 Haiku build test runs another 10% faster, now. The total kernel
time drops about 18%. As hoped the new locks have only a fraction of the old
"pages" lock contention. Other locks lead the "most wanted list" now.



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34933 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 5800e8a4 03-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Moved the page management functionality into its own file.
* Renamed page_queue to VMPageQueue and made it a proper C++ class. Use
DoublyLinkedList instead of own list code.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34874 a95241bf-73f2-0310-859d-f6bbb57e9c96


# eb8dc1eb 27-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

* Removed DEBUG_PAGE_CACHE_TRANSITIONS debugging.
* Added VMCache::MovePage() and MoveAllPages() to move pages between caches.
* VMAnonymousCache:
- _MergeSwapPages(): Avoid doing anything, if neither cache has swapped out
pages.
- _MergeSwapPages() does now also remove source cache pages that are
shadowed by consumer swap pages. This allows us to call _MergeSwapPages()
before _MergePagesSmallerSource(), save the swap page shadowing check
there and get rid of the vm_page::merge_swap flag. This is an
optimization based on the assumption that usually none or only few pages
are swapped out, so we save a lot of checks.
- Implemented _MergePagesSmallerConsumer() as an alternative to
_MergePagesSmallerSource(). The former is used when the source cache has
more pages than the consumer cache. It iterates over the consumer cache's
pages, moves them to the source and finally moves all pages back to the
consumer. The final move is relatively cheap (though unfortunately we
still have to update all pages' vm_page::cache field), so that overall we
save iterations of the main loop with the more expensive checks.

The optimizations particularly improve the common fork()+exec*() situations.
fork() uses CoW, which is implemented by putting two new empty caches between
the to be copied area and its cache. exec*() destroys one copy of the area,
its cache and thus causes merging of the other new cache with the old cache.
Since this usually happens in a very short time, the old cache does still
contain many pages and the new cache only few. Previously the many pages were
all checked and moved individually. Now we do that for the few pages instead.

A very extreme example of this situation is the Haiku image build. jam has a
huge heap (> 200 MB) and it fork()s+exec*()s for every action to be executed.
Since during the cache merging the cache is locked, any write access to a
heap page causes jam to block until the cache merging is done. Formerly that
took so long that it killed a lot of parallelism in multi-job builds. That
could be observed particularly well when lots of small actions where executed
(like the Link, XRes, Mimeset, SetType, SetVersion combos when building
executables/libraries/add-ons). Those look dramatically better now.
The overall speed improvement for a -j8 image build on my machine is only
about 15%, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34784 a95241bf-73f2-0310-859d-f6bbb57e9c96


# be7328a9 07-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

Moved VMCache related definitions to <vm/VMCache.h>.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34535 a95241bf-73f2-0310-859d-f6bbb57e9c96


# f34a1dd5 02-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

Created VMArea.{h,cpp} and moved VMArea and the global area hash table (new
class VMAreaHash) there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34450 a95241bf-73f2-0310-859d-f6bbb57e9c96


# e50cf876 02-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

* Moved the VM headers into subdirectory vm/.
* Renamed vm_cache.h/vm_address_space.h to VMCache.h/VMAddressSpace.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34449 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 73ad2473e7874b3702cf5b0fdf4c81b747812ed9 05-Nov-2013 Pawel Dziepak <pdziepak@quarnos.org>

Remove remaining unnecessary 'volatile' qualifiers


# 90c6930ebba06f6c9b220e712a53c063a542062a 04-Nov-2011 Michael Lotz <mmlr@mlotz.ch>

Add VM page allocation tracking similar to what happens in the slab already.
Introduces "page_allocation_infos" and "page_allocations_per_caller" KDL
commands.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@43190 a95241bf-73f2-0310-859d-f6bbb57e9c96


# b9447668707741085389f650383b018d33d7d0bf 10-Jul-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Moved the vm_page initialization from vm_page.cpp:vm_page_init() to the new
vm_page::Init().
* Made vm_page::wired_count private and added accessor methods.
* Added VMCache::fWiredPagesCount (the number of wired pages the cache
contains) and accessor methods.
* Made more use of vm_page::IsMapped().
* vm_copy_on_write_area(): Added vm_page_reservation* parameter that can be
used to request a special handling for wired pages. If given the wired pages
are replaced by copies and the original pages are moved to the upper cache.
* vm_copy_area():
- We don't need to do any wired ranges handling, if the source area is a
B_SHARED_AREA, since we don't touch the area's mappings in this case.
- We no longer wait for wired ranges of the concerned areas to disappear.
Instead we use the new vm_copy_on_write_area() feature and just let it
copy the wired pages. This fixes #6288, an issue introduced with the use
of user mutexes in libroot: When executing multiple concurrent fork()s all
but the first one would wait on the fork mutex, which (being a user mutex)
would wire a page that the vm_copy_area() of the first fork() would wait
for.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37460 a95241bf-73f2-0310-859d-f6bbb57e9c96


# a8ad734f1c698917badb15e1641e0f38b3e9a013 14-Jun-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Introduced structures {virtual,physical}_address_restrictions, which specify
restrictions for virtual/physical addresses.
* vm_page_allocate_page_run():
- Fixed conversion of base/limit to array indexes. sPhysicalPageOffset was not
taken into account.
- Takes a physical_address_restrictions instead of base/limit and also
supports alignment and boundary restrictions, now.
* map_backing_store(), VM[User,Kernel]AddressSpace::InsertArea()/
ReserveAddressRange() take a virtual_address_restrictions parameter, now. They
also support an alignment independent from the range size.
* create_area_etc(), vm_create_anonymous_area(): Take
{virtual,physical}_address_restrictions parameters, now.
* Removed no longer needed B_PHYSICAL_BASE_ADDRESS.
* DMAResources:
- Fixed potential overflows of uint32 when initializing from device node
attributes.
- Fixed bounce buffer creation TODOs: By using create_area_etc() with the
new restrictions parameters we can directly support physical high address,
boundary, and alignment.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37131 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 147133b76cbb1603bdbff295505f5b830cb4e688 25-May-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* First run through the kernel's private parts to use phys_{addr,size}_t
where appropriate.
* Typedef'ed page_num_t to phys_addr_t and used it in more places in
vm_page.{h,cpp}.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36937 a95241bf-73f2-0310-859d-f6bbb57e9c96


# fe0963a83539b139455a49d17a0e7fe1b98090aa 18-Mar-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

Added commands to the page access debugging panic()s.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35904 a95241bf-73f2-0310-859d-f6bbb57e9c96


# bd7645a12ab594d5eb1c6d6a70c3a82a429410dd 20-Feb-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Made vm_page::state private and added accessor methods.
* Added kernel tracing for page state transitions.



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35538 a95241bf-73f2-0310-859d-f6bbb57e9c96


# d36b9aef3edc3fb15cea5a29f51d83a1ac4168d1 19-Feb-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

Added vm_page::IsMapped() for convenience.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35531 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 40bb94819e6c39d72ab29edc1a0dcd80b15b8b42 03-Feb-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Removed useless return parameter from vm_remove_all_page_mappings().
* Added vm_clear_page_mapping_accessed_flags() and
vm_remove_all_page_mappings_if_unaccessed(), which combine the functionality
of vm_test_map_activation(), vm_clear_map_flags(), and
vm_remove_all_page_mappings(), thus saving lots of calls to translation map
methods. The backend is the new method
VMTranslationMap::ClearAccessedAndModified().
* Started to make use of the cached page queue and changed the meaning of the
other non-free queues slightly:
- Active queue: Contains mapped pages that have been used recently.
- Inactive queue: Contains mapped pages that have not been used recently. Also
contains unmapped temporary pages.
- Modified queue: Contains unmapped modified pages.
- Cached queue: Contains unmapped unmodified pages (LRU sorted).
Unless we're actually low on memory and actively do paging, modified and
cached queues only contain non-temporary pages. Cached pages are considered
quasi free. They still belong to a cache, but since they are unmodified and
unmapped, they can be freed immediately. And this is what
vm_page_[try_]reserve_pages() do now when there are no more actually free
pages at hand. Essentially this means that pages storing cached file data,
unless mmap()ped, no longer are considered used and don't contribute to page
pressure. Paging will not happen as long there are enough free + cached pages
available.
* Reimplemented the page daemon. It no longer scans all pages, but instead works
the page queues. As long as the free pages situation is harmless, it only
iterates through the active queue and deactivates pages that have not been
used recently. When paging occurs it additionally scans the inactive queue and
frees pages that have not been used recently.
* Changed the page reservation/allocation interface:
vm_page_[try_]reserve_pages(), vm_page_unreserve_pages(), and
vm_page_allocate_page() now take a vm_page_reservation structure pointer.
The reservation functions initialize the structure -- currently consisting
only of a count member for the number of still reserved pages.
vm_page_allocate_page() decrements the count and vm_page_unreserve_pages()
unreserves the remaining pages (if any). Advantages are that reservation/
unreservation mismatches cannot occur anymore, that vm_page_allocate_page()
can verify that the caller has indeed a reserved page left, and that there's
no unnecessary pressure on the free page pool anymore. The only disadvantage
is that the vm_page_reservation object needs to be passed around a bit.
* Reworked the page reservation implementation:
- Got rid of sSystemReservedPages and sPageDeficit. Instead
sUnreservedFreePages now actually contains the number of free pages that
have not yet been reserved (it cannot become negative anymore) and the new
sUnsatisfiedPageReservations contains the number of pages that are still
needed for reservation.
- Threads waiting for reservations do now add themselves to a waiter queue,
which is ordered by descending priority (VM priority and thread priority).
High priority waiters are served first when pages become available.
Fixes #5328.
* cache_prefetch_vnode(): Would reserve one less page than allocated later, if
the size wasn't page aligned.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35393 a95241bf-73f2-0310-859d-f6bbb57e9c96


# e65c400299386f99a251395ff2e59572705d7e49 29-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Replaced the vm_page_allocate_page*() "pageState" parameter by a more
general "flags" parameter. It encodes the target state of the page -- so
that the page isn't unnecessarily put in the wrong page queue first -- a
flag whether the page should be cleared, and one to indicate whether the
page should be marked busy.
* Added page state PAGE_STATE_CACHED. Not used yet.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35333 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 72382fa6291e810be2949a70abd8f274f92dbd2c 29-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Removed the page state PAGE_STATE_BUSY and instead introduced a vm_page::busy
flag. The obvious advantage is that one can still see what state a page is in
and even move it between states while being marked busy.
* Removed the vm_page::is_dummy flag. Instead we mark marker pages busy, which
in all cases has the same effect. Introduced a vm_page_is_dummy() that can
still check whether a given page is a dummy page.
* vm_page_unreserve_pages(): Before adding to the system reserve make sure
sUnreservedFreePages is non-negative. Otherwise we'd make nonexisting pages
available for allocation. steal_pages() still has the same problem and it
can't be solved that easily.
* map_page(): No longer changes the page state/mark the page unbusy. That's the
caller's responsibility.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35331 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 6379e53e2dd7021ba0e35d41c276dfe94c079596 19-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

vm_page no longer points directly to its containing cache, but rather to a
VMCacheRef object which points to the cache. This allows to optimize
VMCache::MoveAllPages(), since it no longer needs to iterate over all pages
to adjust their cache pointer. It can simple swap the cache refs of the two
caches instead.

Reduces the total -j8 Haiku image build time only marginally. The kernel time
drops almost 10%, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35155 a95241bf-73f2-0310-859d-f6bbb57e9c96


# f082f7f019941732f1d2b99f627fbeeeec3746af 15-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Added vm_page::accessed flag. Works analogously to vm_page::modified.
* Reorganized the code for [un]mapping pages:
- Added new VMTranslationMap::Unmap{Area,Page[s]}() which essentially do what
vm_unmap_page[s]() did before, just in the architecture specific code, which
allows for specific optimizations. UnmapArea() is for the special case that
the complete area is unmapped. Particularly in case the address space is
deleted, some work can be saved. Several TODOs could be slain.
- Since they are only used within vm.cpp vm_map_page() and vm_unmap_page[s]()
are now static and have lost their prefix (and the "preserveModified"
parameter).
* Added VMTranslationMap::Protect{Page,Area}(). They are just inline wrappers
for Protect().
* X86VMTranslationMap::Protect(): Make sure not to accidentally clear the
accessed/dirty flags.
* X86VMTranslationMap::Unmap()/Protect(): Make page table skipping actually
work. It was only skipping to the next page.
* Adjusted the PPC code to at least compile.

No measurable effect for the -j8 Haiku image build time, though the kernel time
drops minimally.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35089 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 3b8c056da097f1b7386f013726bb3ad13ea2ef98 11-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

Should have been part of r35023: Introduction of the vm_page::modified flag.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35024 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 451ca8b4b43e650a8c6cd7edd7f59640ebfee7f9 11-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

PAGE_TYPE_GUARD was unused and for the other two types a simple one bit flag
suffices. Therefore replaced vm_page::type by vm_page::is_dummy.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35013 a95241bf-73f2-0310-859d-f6bbb57e9c96


# d7455de2f603518cf6470bbca9aa19fe5a41c4ca 11-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

allocate_page_run(): Use temporary lists to store the pages we're allocating.
This makes appending the pages to the active queue more efficient and we
don't need the vm_page::is_cleared bit anymore.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35011 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 3cd2094396dde9ca42263c535041a95d5f0d5fff 06-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Added new debug feature (DEBUG_PAGE_ACCESS) to detect invalid concurrent
access to a vm_page. It is basically an atomically accessed thread ID field
in the vm_page structure, which is explicitly set by macros marking the
critical sections. As a first positive effect I had to review quite a bit of
code and found several issues.
* Added several TODOs and comments. Some harmless ones, but also a few
troublesome ones in vm.cpp regarding page unmapping.
* file_cache: PrecacheIO::Prepare()/read_into_cache: Removed superfluous
vm_page_allocate_page() return value checks. It cannot fail anymore.
* Removed the heavily contended "pages" lock. We use different policies now:
- sModifiedTemporaryPages is accessed atomically.
- sPageDeficitLock and sFreePageCondition are protected by a new mutex.
- The page queues have individual locks (mutexes).
- Renamed set_page_state_nolock() to set_page_state(). Unless the caller says
otherwise, it does now lock the affected pages queues itself. Also changed
the return value to void -- we panic() anyway.
* set_page_state(): Add free/clear pages to the beginning of their respective
queues as this is more cache-friendly.
* Pages with the states PAGE_STATE_WIRED or PAGE_STATE_UNUSED are no longer
in any queue. They were in the "active" queue, but there's no good reason
to have them there. In case we decide to let the page daemon work the queues
(like FreeBSD) they would just be in the way.
* Pulled the common part of vm_page_allocate_page_run[_no_base]() into a helper
function. Also fixed a bug I introduced previously: The functions must not
vm_page_unreserve_pages() on success, since they remove the pages from the
free/clear queue without decrementing sUnreservedFreePages.
* vm_page_set_state(): Changed return type to void. The function cannot really
fail and no-one was checking it anyway.
* vm_page_free(), vm_page_set_state(): Added assertion: The page must not be
free/clear before. This is implied by the policy that no-one is allowed to
access free/clear pages without holding the respective queue's lock, which is
not the case at this point. This found the bug fixed in r34912.
* vm_page_requeue(): Added general assertions. panic() when requeuing of
free/clear pages is requested. Same reason as above.
* vm_clone_area(), B_FULL_LOCK case: Don't map busy pages. The implementation is
still not correct, though.

My usual -j8 Haiku build test runs another 10% faster, now. The total kernel
time drops about 18%. As hoped the new locks have only a fraction of the old
"pages" lock contention. Other locks lead the "most wanted list" now.



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34933 a95241bf-73f2-0310-859d-f6bbb57e9c96


# 5800e8a486993399f7f68be67099dc64bdb8a4be 03-Jan-2010 Ingo Weinhold <ingo_weinhold@gmx.de>

* Moved the page management functionality into its own file.
* Renamed page_queue to VMPageQueue and made it a proper C++ class. Use
DoublyLinkedList instead of own list code.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34874 a95241bf-73f2-0310-859d-f6bbb57e9c96


# eb8dc1ebfbe911a6af06efe02d003aa37687faad 27-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

* Removed DEBUG_PAGE_CACHE_TRANSITIONS debugging.
* Added VMCache::MovePage() and MoveAllPages() to move pages between caches.
* VMAnonymousCache:
- _MergeSwapPages(): Avoid doing anything, if neither cache has swapped out
pages.
- _MergeSwapPages() does now also remove source cache pages that are
shadowed by consumer swap pages. This allows us to call _MergeSwapPages()
before _MergePagesSmallerSource(), save the swap page shadowing check
there and get rid of the vm_page::merge_swap flag. This is an
optimization based on the assumption that usually none or only few pages
are swapped out, so we save a lot of checks.
- Implemented _MergePagesSmallerConsumer() as an alternative to
_MergePagesSmallerSource(). The former is used when the source cache has
more pages than the consumer cache. It iterates over the consumer cache's
pages, moves them to the source and finally moves all pages back to the
consumer. The final move is relatively cheap (though unfortunately we
still have to update all pages' vm_page::cache field), so that overall we
save iterations of the main loop with the more expensive checks.

The optimizations particularly improve the common fork()+exec*() situations.
fork() uses CoW, which is implemented by putting two new empty caches between
the to be copied area and its cache. exec*() destroys one copy of the area,
its cache and thus causes merging of the other new cache with the old cache.
Since this usually happens in a very short time, the old cache does still
contain many pages and the new cache only few. Previously the many pages were
all checked and moved individually. Now we do that for the few pages instead.

A very extreme example of this situation is the Haiku image build. jam has a
huge heap (> 200 MB) and it fork()s+exec*()s for every action to be executed.
Since during the cache merging the cache is locked, any write access to a
heap page causes jam to block until the cache merging is done. Formerly that
took so long that it killed a lot of parallelism in multi-job builds. That
could be observed particularly well when lots of small actions where executed
(like the Link, XRes, Mimeset, SetType, SetVersion combos when building
executables/libraries/add-ons). Those look dramatically better now.
The overall speed improvement for a -j8 image build on my machine is only
about 15%, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34784 a95241bf-73f2-0310-859d-f6bbb57e9c96


# be7328a9f6b3c55eec71d403a0367d80fd4ebd12 07-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

Moved VMCache related definitions to <vm/VMCache.h>.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34535 a95241bf-73f2-0310-859d-f6bbb57e9c96


# f34a1dd5d701373687b6f3f0e6e76bd2b1ae6007 02-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

Created VMArea.{h,cpp} and moved VMArea and the global area hash table (new
class VMAreaHash) there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34450 a95241bf-73f2-0310-859d-f6bbb57e9c96


# e50cf8765be50a7454c9488db38b638cf90805af 02-Dec-2009 Ingo Weinhold <ingo_weinhold@gmx.de>

* Moved the VM headers into subdirectory vm/.
* Renamed vm_cache.h/vm_address_space.h to VMCache.h/VMAddressSpace.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34449 a95241bf-73f2-0310-859d-f6bbb57e9c96