drm2: whack set-but-not-used warns

sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Merge ^/head r358400 through r358465.

Convert a few triviail consumers to the new unlocked grab API.

Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D23847

(4/6) Protect page valid with the busy lock.

Atomics are used for page busy and valid state when the shared busy is
held. The details of the locking protocol and valid and dirty
synchronization are

(4/6) Protect page valid with the busy lock.

Atomics are used for page busy and valid state when the shared busy is
held. The details of the locking protocol and valid and dirty
synchronization are in the updated vm_page.h comments.

Reviewed by: kib, markj
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D21594

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Merge ^/head r352105 through r352307.

Replace redundant code with a few new vm_page_grab facilities:
- VM_ALLOC_NOCREAT will grab without creating a page.
- vm_page_grab_valid() will grab and page in if necessary.
- vm_page_busy_acqui

Replace redundant code with a few new vm_page_grab facilities:
- VM_ALLOC_NOCREAT will grab without creating a page.
- vm_page_grab_valid() will grab and page in if necessary.
- vm_page_busy_acquire() automates some busy acquire loops.

Discussed with: alc, kib, markj
Tested by: pho (part of larger branch)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21546

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Change synchonization rules for vm_page reference counting.

There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
pa

Change synchonization rules for vm_page reference counting.

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

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Revert drm2 removal.

Revert r338177, r338176, r338175, r338174, r338172

After long consultations with re@, core members and mmacy, revert
these changes. Followup changes will be made to mark them a

Revert drm2 removal.

Revert r338177, r338176, r338175, r338174, r338172

After long consultations with re@, core members and mmacy, revert
these changes. Followup changes will be made to mark them as
deprecated and prent a message about where to find the up-to-date
driver. Followup commits will be made to make this clear in the
installer. Followup commits to reduce POLA in ways we're still
exploring.

It's anticipated that after the freeze, this will be removed in
13-current (with the residual of the drm2 code copied to
sys/arm/dev/drm2 for the TEGRA port's use w/o the intel or
radeon drivers).

Due to the impending freeze, there was no formal core vote for
this. I've been talking to different core members all day, as well as
Matt Macey and Glen Barber. Nobody is completely happy, all are
grudgingly going along with this. Work is in progress to mitigate
the negative effects as much as possible.

Requested by: re@ (gjb, rgrimes)

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MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

MFH @r292599

This includes the pluggable TCP framework and other chnages to the
netstack to track for VNET stability.

Security: The FreeBSD Foundation

A change to KPI of vm_pager_get_pages() and underlying VOP_GETPAGES().

o With new KPI consumers can request contiguous ranges of pages, and
unlike before, all pages will be kept busied on return,

A change to KPI of vm_pager_get_pages() and underlying VOP_GETPAGES().

o With new KPI consumers can request contiguous ranges of pages, and
unlike before, all pages will be kept busied on return, like it was
done before with the 'reqpage' only. Now the reqpage goes away. With
new interface it is easier to implement code protected from race
conditions.

Such arrayed requests for now should be preceeded by a call to
vm_pager_haspage() to make sure that request is possible. This
could be improved later, making vm_pager_haspage() obsolete.

Strenghtening the promises on the business of the array of pages
allows us to remove such hacks as swp_pager_free_nrpage() and
vm_pager_free_nonreq().

o New KPI accepts two integer pointers that may optionally point at
values for read ahead and read behind, that a pager may do, if it
can. These pages are completely owned by pager, and not controlled
by the caller.

This shifts the UFS-specific readahead logic from vm_fault.c, which
should be file system agnostic, into vnode_pager.c. It also removes
one VOP_BMAP() request per hard fault.

Discussed with: kib, alc, jeff, scottl
Sponsored by: Nginx, Inc.
Sponsored by: Netflix

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Merge head r233826 through r256722.

IFC @256277

Approved by: ken (mentor)

IFC @ r255692

Comment out IA32_MISC_ENABLE MSR access - this doesn't exist on AMD.
Need to sort out how arch-specific MSRs will be handled.

Merge from head

IFC @ r255209

MFC

ttm: "to_page->valid = VM_PAGE_BITS_ALL" before vm_page_dirty(to_page)

Approved by; kib@

MFC

Remove the deprecated VM_ALLOC_RETRY flag for the vm_page_grab(9).
The flag was mandatory since r209792, where vm_page_grab(9) was
changed to only support the alloc retry semantic.

Suggested and rev

Remove the deprecated VM_ALLOC_RETRY flag for the vm_page_grab(9).
The flag was mandatory since r209792, where vm_page_grab(9) was
changed to only support the alloc retry semantic.

Suggested and reviewed by: alc
Sponsored by: The FreeBSD Foundation

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The soft and hard busy mechanism rely on the vm object lock to work.
Unify the 2 concept into a real, minimal, sxlock where the shared
acquisition represent the soft busy and the exclusive acquisitio

The soft and hard busy mechanism rely on the vm object lock to work.
Unify the 2 concept into a real, minimal, sxlock where the shared
acquisition represent the soft busy and the exclusive acquisition
represent the hard busy.
The old VPO_WANTED mechanism becames the hard-path for this new lock
and it becomes per-page rather than per-object.
The vm_object lock becames an interlock for this functionality:
it can be held in both read or write mode.
However, if the vm_object lock is held in read mode while acquiring
or releasing the busy state, the thread owner cannot make any
assumption on the busy state unless it is also busying it.

Also:
- Add a new flag to directly shared busy pages while vm_page_alloc
and vm_page_grab are being executed. This will be very helpful
once these functions happen under a read object lock.
- Move the swapping sleep into its own per-object flag

The KPI is heavilly changed this is why the version is bumped.
It is very likely that some VM ports users will need to change
their own code.

Sponsored by: EMC / Isilon storage division
Discussed with: alc
Reviewed by: jeff, kib
Tested by: gavin, bapt (older version)
Tested by: pho, scottl

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IFC @ r254014

IFC @253398

Merge fresh head.