Revert r212370, as it causes a LOR on powerpc. powerpc does a few
unexpected things in copyout(9) and so wiring the user buffer is not
sufficient to perform a copyout(9) while holding a random mutex

Revert r212370, as it causes a LOR on powerpc. powerpc does a few
unexpected things in copyout(9) and so wiring the user buffer is not
sufficient to perform a copyout(9) while holding a random mutex.

Requested by: nwhitehorn

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Add a drain function for struct sysctl_req, and use it for a variety of
handlers, some of which had to do awkward things to get a large enough
FIXEDLEN buffer.

Note that some sysctl handlers were ex

Add a drain function for struct sysctl_req, and use it for a variety of
handlers, some of which had to do awkward things to get a large enough
FIXEDLEN buffer.

Note that some sysctl handlers were explicitly outputting a trailing NUL
byte. This behaviour was preserved, though it should not be necessary.

Reviewed by: phk

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Merge from head

- Merge from HEAD

Previously, when vm_page_free_toq() was performed on a page belonging to
a reservation, unless all of the reservation's pages were free, the
reservation was moved to the head of the partially-populat

Previously, when vm_page_free_toq() was performed on a page belonging to
a reservation, unless all of the reservation's pages were free, the
reservation was moved to the head of the partially-populated reservations
queue, where it would be the next reservation to be broken in case the
free page queues were emptied. Now, instead, I am moving it to the tail.
Very likely this reservation is in the process of being freed in its
entirety, so placing it at the tail of the queue makes it more likely that
the underlying physical memory will be returned to the free page queues as
one contiguous chunk. If a reservation must be broken, it will, instead,
be the longest unchanged reservation, which is arguably the reservation
that is least likely to ever achieve promotion or be freed in its entirety.

MFC after: 6 weeks

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Introduce vm_reserv_reclaim_contig(). This function is used by
contigmalloc(9) as a last resort to steal pages from an inactive,
partially-used superpage reservation.

Rename vm_reserv_reclaim() to

Introduce vm_reserv_reclaim_contig(). This function is used by
contigmalloc(9) as a last resort to steal pages from an inactive,
partially-used superpage reservation.

Rename vm_reserv_reclaim() to vm_reserv_reclaim_inactive() and
refactor it so that a separate subroutine is responsible for breaking
the selected reservation. This subroutine is also used by
vm_reserv_reclaim_contig().

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Add the superpage reservation system. This is "part 2 of 2" of the
machine-independent support for superpages. (The earlier part was
the rewrite of the physical memory allocator.) The remainder of

Add the superpage reservation system. This is "part 2 of 2" of the
machine-independent support for superpages. (The earlier part was
the rewrite of the physical memory allocator.) The remainder of the
code required for superpages support is machine-dependent and will
be added to the various pmap implementations at a later date.

Initially, I am only supporting one large page size per architecture.
Moreover, I am only enabling the reservation system on amd64. (In
an emergency, it can be disabled by setting VM_NRESERVLEVELS to 0
in amd64/include/vmparam.h or your kernel configuration file.)

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- Merge from HEAD

Previously, when vm_page_free_toq() was performed on a page belonging to
a reservation, unless all of the reservation's pages were free, the
reservation was moved to the head of the partially-populat

Previously, when vm_page_free_toq() was performed on a page belonging to
a reservation, unless all of the reservation's pages were free, the
reservation was moved to the head of the partially-populated reservations
queue, where it would be the next reservation to be broken in case the
free page queues were emptied. Now, instead, I am moving it to the tail.
Very likely this reservation is in the process of being freed in its
entirety, so placing it at the tail of the queue makes it more likely that
the underlying physical memory will be returned to the free page queues as
one contiguous chunk. If a reservation must be broken, it will, instead,
be the longest unchanged reservation, which is arguably the reservation
that is least likely to ever achieve promotion or be freed in its entirety.

MFC after: 6 weeks

show more ...

Introduce vm_reserv_reclaim_contig(). This function is used by
contigmalloc(9) as a last resort to steal pages from an inactive,
partially-used superpage reservation.

Rename vm_reserv_reclaim() to

Introduce vm_reserv_reclaim_contig(). This function is used by
contigmalloc(9) as a last resort to steal pages from an inactive,
partially-used superpage reservation.

Rename vm_reserv_reclaim() to vm_reserv_reclaim_inactive() and
refactor it so that a separate subroutine is responsible for breaking
the selected reservation. This subroutine is also used by
vm_reserv_reclaim_contig().

show more ...

Add the superpage reservation system. This is "part 2 of 2" of the
machine-independent support for superpages. (The earlier part was
the rewrite of the physical memory allocator.) The remainder of

Add the superpage reservation system. This is "part 2 of 2" of the
machine-independent support for superpages. (The earlier part was
the rewrite of the physical memory allocator.) The remainder of the
code required for superpages support is machine-dependent and will
be added to the various pmap implementations at a later date.

Initially, I am only supporting one large page size per architecture.
Moreover, I am only enabling the reservation system on amd64. (In
an emergency, it can be disabled by setting VM_NRESERVLEVELS to 0
in amd64/include/vmparam.h or your kernel configuration file.)

show more ...