There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
particular, holding the page's object lock is sufficient to prevent the
page from being freed; holding the busy lock or a wiring is sufficent as
well. These references are protected by the page lock, which must
therefore be acquired for many per-page operations. This results in
false sharing since the page locks are external to the vm_page
structures themselves and each lock protects multiple structures.
Transition to using an atomically updated per-page reference counter.
The object's reference is counted using a flag bit in the counter. A
second flag bit is used to atomically block new references via
pmap_extract_and_hold() while removing managed mappings of a page.
Thus, the reference count of a page is guaranteed not to increase if the
page is unbusied, unmapped, and the object's write lock is held. As
a consequence of this, the page lock no longer protects a page's
identity; operations which move pages between objects are now
synchronized solely by the objects' locks.
The vm_page_wire() and vm_page_unwire() KPIs are changed. The former
requires that either the object lock or the busy lock is held. The
latter no longer has a return value and may free the page if it releases
the last reference to that page. vm_page_unwire_noq() behaves the same
as before; the caller is responsible for checking its return value and
freeing or enqueuing the page as appropriate. vm_page_wire_mapped() is
introduced for use in pmap_extract_and_hold(). It fails if the page is
concurrently being unmapped, typically triggering a fallback to the
fault handler. vm_page_wire() no longer requires the page lock and
vm_page_unwire() now internally acquires the page lock when releasing
the last wiring of a page (since the page lock still protects a page's
queue state). In particular, synchronization details are no longer
leaked into the caller.
The change excises the page lock from several frequently executed code
paths. In particular, vm_object_terminate() no longer bounces between
page locks as it releases an object's pages, and direct I/O and
sendfile(SF_NOCACHE) completions no longer require the page lock. In
these latter cases we now get linear scalability in the common scenario
where different threads are operating on different files.
__FreeBSD_version is bumped. The DRM ports have been updated to
accomodate the KPI changes.
Reviewed by: jeff (earlier version)
Tested by: gallatin (earlier version), pho
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20486
This patch makes the DRM graphics driver in ports usable on aarch64.
Submitted by: Greg V <greg@unrelenting.technology>
Differential Revision: https://reviews.freebsd.org/D21008
MFC after: 1 week
Sponsored by: Mellanox Technologies
The DRM drivers use the lockdep assertion macros with spinlock_t locks
which are backed by mutexes, not sx locks. This causes compile
failures since you can't use sx_assert with a mutex. Instead, change
the lockdep macros to use lock_class methods. This works by assuming
that each LinuxKPI locking primitive embeds a FreeBSD lock as its
first structure and uses a cast to get to the underlying 'struct
lock_object'.
Reviewed by: hselasky
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20992
PowerPC, and possibly other architectures, use different address ranges for
PCI space vs physical address space, which is only mapped at resource
activation time, when the BAR gets written. The DRM kernel modules do not
activate the rman resources, soas not to waste KVA, instead only mapping
parts of the PCI memory at a time. This introduces a
BUS_TRANSLATE_RESOURCE() method, implemented in the Open Firmware/FDT PCI
driver, to perform this necessary translation without activating the
resource.
In addition to system KPI changes, LinuxKPI is updated to handle a
big-endian host, by adding proper endian swaps to the I/O functions.
Submitted by: mmacy
Reported by: hselasky
Differential Revision: https://reviews.freebsd.org/D21096
LINUXKPI_VERSION macro is not defined for any compiled LinuxKPI code
which basically means __GFP_NOTWIRED is never checked when allocating
pages. This should work fine with the existing external DRM code as
long as the page wiring and unwiring is balanced.
MFC after: 3 days
Sponsored by: Mellanox Technologies
- Add rcu list functions.
- Make rcu hlist's foreach macro use rcu calls instead of the non-rcu macro.
- Bump FreeBSD version so we have a checkpoint for the vboxvideo drm driver.
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Differential Revision: D20719
Previously it did this only on platforms without a direct map. This
also more closely matches Linux's semantics.
Since some DRM v5.0 code assumes the old behaviour, use a
LINUXKPI_VERSION guard to preserve that until the out-of-tree module
is updated.
Reviewed by: hselasky, kib (earlier versions), johalun
MFC after: 1 week
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20502
seq_file.h and linux_seq_file.c was imported form ports earlier but
linux_seq_file.c was never compiled in with the module. With this
commit base seq_file will replace ports seq_file and it required a
few modifications to not break functionality and build.
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
DRM drivers expect tasklets to have a counter for enable/disable calls.
Also, add a few more tasklet locking functions.
This patch is part of D19565
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Assign self as group leader at creation to act as the only member of a
new process group.
This patch is part of D19565
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Check LINUXKPI_VERSION macro for backwards compatibility.
It's recommended to update any drivers that depend on the older KPI
so we can deprecate < 5.0 code as we update to newer Linux version.
This patch is part of D19565
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Check the new LINUXKPI_VERSION macro for backwards compatibility.
This patch is part of D19565
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Also, make ktime_get_raw call getnanouptime instead of getnanotime
to match (the correct) ktime_get_raw_ns.
This patch is part of D19565
Reviewed by: hps
Approved by: imp (mentor), hps
MFC after: 1 week
Add support for DIM based on Linux,
with some minor adaptions specific to FreeBSD.
Linux commit
f97c3dc3c0e8d23a5c4357d182afeef4c67f5c33
MFC after: 3 days
Sponsored by: Mellanox Technologies
As Linux comment for this function point:
Signal to the system that the PCI device is not in use by the system
anymore. This only involves disabling PCI bus-mastering, if active.
Build tested drm-current-kmod prior to commit.
MFC after: 1 week
Submitted by: slavash@
Sponsored by: Mellanox Technologies
Turning on pr_debug at compile time make it non-optional at runtime.
This often means that the amount of the debugging is unbearable.
Allow developer to turn on pr_debug output only when needed.
Build tested drm-current-kmod prior to commit.
MFC after: 1 week
Submitted by: kib@
Sponsored by: Mellanox Technologies
The S/G list must be mapped AS-IS without any optimisations.
This also implies that sg_dma_len() must be equal to sg->length.
Many Linux drivers assume this and this fixes some DRM issues.
Put the BUS DMA map pointer into the scatter-gather list to
allow multiple mappings on the same physical memory address.
The FreeBSD version has been bumped to force recompilation of
external kernel modules.
Sponsored by: Mellanox Technologies
