- Use spinlock_enter()/spinlock_exit() to prevent a thread holding a
debug lock from being preempted to prevent other threads waiting
on that lock from starvation.
- Handle the possibility of CPU migration in between the fetch of curcpu
and the call to spinlock_enter() by saving curcpu in a local variable.
- Use memory barriers to prevent reordering of loads and stores of the
data protected by the lock outside of the critical section
- Eliminate false sharing of the locks by moving them into the structures
that they protect and aligning them to a cacheline boundary.
- Record the owning thread in the lock to make debugging future problems
easier.
Reviewed by: rpaulo (initial version)
MFC after: 2 weeks
'"'. Mangling is only done for label names read from file system
metadata. Encoding resembles URL encoding. For example, the space
character becomes %20.
Help by: kib
Discussed with: imp, kib, pjd
interrupt context can still be idlethread. At that point, without the
panic condition, it can still happen that idlethread then will try to
acquire some locks to carry on some operations.
Skip the idlethread check on block/sleep lock operations when KDB is
active.
Reported by: jh
Tested by: jh
MFC after: 1 week
processing. For if_transmit() style hardware drivers (which none publicly
exist yet, for wireless) they will need to still implement if_start()
but only to re-start the TX queue.
allocate a map or mapping resources. That seems to imply that any memory
allocations it does must use M_NOWAIT and check for NULL.
Submitted by: Ian Lepore <freebsd@damnhippie.dyndns.org>
elements to the USB audio softc structure. This fixes a double CPU
fault when attaching USB audio devices in 10-current for i386 at
least.
MFC after: 1 week
Use a boundary of zero, hence a PAGE_SIZE boundary
is implied by all memory allocations.
Background:
Busdma has problems to allocate more than PAGE_SIZE
bytes when the boundary is PAGE_SIZE bytes too.
Initially it was thought that a boundary of PAGE_SIZE
bytes will only affect loading of DMA memory, so that
segments get split correctly, but it also affects
allocation of DMA'able memory.
Solution:
USB can detect big segments and split them as required
by the USB code.
MFC after: 1 week
Reported by: gonzo
When kern_yield() was introduced with the possibility to specify
a new priority, the behaviour changed by not lowering priority at all
in the consumers, making the yielding mechanism highly ineffective for
high priority kthreads like bufdaemon, syncer, vlrudaemon, etc.
There are no evidences that consumers could bear with such change in
semantic and this situation could finally lead to bugs similar to the
ones fixed in r244240.
Re-specify userland pri for kthreads involved.
Tested by: pho
Reviewed by: kib, mdf
MFC after: 1 week
previous names, 'ptag' and 'pmap' -- p stands for packet.
This change reduces the difference between the code in stable/9
and head, and also helps using the same ixgbe_netmap.h on both branches.
Approved by: Jack Vogel
through the USB API and/or busdma.
The following assumptions have been made:
umass - buffers passed from CAM/SCSI layer are OK
network - mbufs are OK.
Some other nits while at it.
MFC after: 1 week
Suggested by: imp
DMA data does not reside next to non DMA data. This
might cause more memory to be allocated, but solves
problems on platforms using manual cache
synchronization.
Add a convenience function to get the buffer only
from a USB transfer's page cache structure.
MFC after: 1 week
Suggested by: imp
Unfortunately 5720S uses 5709S PHY id so add a hack to detect 5720S
PHY by checking parent device name. 5720S PHY does not support 2500SX.
Tested by: Geans Pin < geanspin <> broadcom dot com >
We also try to make better use of the fs flags instead of
trying adapt the code according to the fs structures. In
the case of subsecond timestamps and birthtime we now
check that the feature is explicitly enabled: previously
we only checked that the reserved space was available and
silently wrote them.
This approach is much safer, especially if the filesystem
happens to use embedded inodes or support EAs.
Discussed with: Zheng Liu
MFC after: 5 days
- Use the new architecture-agnostic buffer pool manager that uses uma(9)
to manage a set of power-of-2 sized buffers for bus_dmamem_alloc().
- Create pools of buffers backed by both regular and uncacheable memory,
and use them to handle regular versus BUS_DMA_COHERENT allocations.
- Use uma(9) to manage a pool of bus_dmamap structs instead of local code
to manage a static list of 500 items (it took 3300 maps to get to
multi-user mode, so the static pool wasn't much of an optimization).
- Small BUS_DMA_COHERENT allocations no longer waste an entire page per
allocation, or set pages to uncached when they contain data other than
DMA buffers. There's no longer a need for drivers to work around the
inefficiency by allocing large buffers then sub-dividing them.
- Because we know the alignment and padding of buffers allocated by
bus_dmamem_alloc() (whether coherent or regular memory, and whether
obtained from the pool allocator or directly from the kernel) we
can avoid doing partial cacheline flushes on them.
- Add a fast-out to _bus_dma_could_bounce() (and some comments about
what the routine really does because the old misplaced comment was wrong).
- Everywhere the dma tag alignment is used, the interpretation is that
an alignment of 1 means no special alignment. If the tag is created
with an alignment argument of zero, store it in the tag as one, and
remove all the code scattered around that changed 0->1 at point of use.
- Remove stack-allocated arrays of segments, use a local array of two
segments within the tag struct, or dynamically allocate an array at first
use if nsegments > 2. On an arm system I tested, only 5 of 97 tags used
more than two segments. On my x86 desktop it was only 7 of 111 tags.
Submitted by: Ian Lepore <freebsd@damnhippie.dyndns.org>
manage a set of power-of-2 sized buffers for bus_dmamem_alloc().
This allows the caller to provide the back-end allocator uma allocator,
allowing full control of the memory pages backing the pool. For
convenience, it provides an optional builtin allocator that provides pages
allocated with the VM_MEMATTR_UNCACHEABLE attribute, for managing pools of
DMA buffers for BUS_DMA_COHERENT or BUS_DMA_NOCACHE.
This also allows the caller to specify a minimum alignment, and it ensures
that all buffers start on a boundary and have a length that's a multiple of
that value, to avoid using buffers that trigger partial cache line flushes.
Submitted by: Ian Lepore <freebsd@damnhippie.dyndns.org>
only returns name, but also vnode of corefile to use.
This simplifies the code and closes few races, especially in %I handling.
Reviewed by: kib
Obtained from: WHEEL Systems
- Use this new format to automatically handle syscalls and VOPs. This
changes the earlier format but is still human readable.
Sponsored by: EMC / Isilon Storage Division
