Introduce counter(9) API, that implements fast and raceless counters,
provided (but not limited to) for gathering of statistical data.
See http://lists.freebsd.org/pipermail/freebsd-arch/2013-April/014204.html
for more details.
In collaboration with: kib
Reviewed by: luigi
Tested by: ae, ray
Sponsored by: Nginx, Inc.
most kernels before FreeBSD 9.0. Remove such modules and respective kernel
options: atadisk, ataraid, atapicd, atapifd, atapist, atapicam. Remove the
atacontrol utility and some man pages. Remove useless now options ATA_CAM.
No objections: current@, stable@
MFC after: never
uart(4) allocates send and receiver buffers in attach() before it calls
the low-level driver's attach routine. Many low-level drivers set the
fifo sizes in their attach routine, which is too late. Other drivers set
them in the probe() routine, so that they're available when uart(4)
allocates buffers. This fixes the ones that were setting the values too
late by moving the code to probe().
Changes to make rtc/cts flow control work...
This does not turn on the builtin hardware flow control on the SoC's usart
device, because that doesn't work on uart1 due to a chip erratum (they
forgot to wire up pin PA21 to RTS0 internally). Instead it uses the
hardware flow control logic where the tty layer calls the driver to assert
and de-assert the flow control lines as needed. This prevents overruns at
the tty layer (app doesn't read fast enough), but does nothing for overruns
at the driver layer (interrupts not serviced fast enough).
To work around the wiring problem with RTS0, the driver reassigns that pin
as a GPIO and controls it manually. It only does so if given permission via
hint.uart.1.use_rts0_workaround=1, to prevent accidentally driving the pin
if uart1 is used without flow control (because something not related to
serial IO could be wired to that pin).
In addition to the RTS0 workaround, driver changes were needed in the area
of reading the current set of DCE signals. A priming read is now done at
attach() time, and the interrupt routine now sets SER_INT_SIGCHG when any
of the DCE signals change. Without these changes, nothing could ever be
transmitted, because the tty layer thought CTS was de-asserted (when in fact
we had just never read the status register, and the hwsig variable was
init'd to CTS de-asserted).
Changes to support bulk high-speed (230kbps and higher) data reception...
Allow the receive fifo size to be tuned with hint.uart.<dev>.fifo_bytes.
For high speed receive, a fifo size of 1024 works well. The default is
still 128 bytes if no hint is provided. Using a value larger than 384
requires a change in dev/uart/uart_core.c to size the intermediate
buffer as MAX(384, 3*sc->sc_rxfifosize).
Recalculate the receive timeout whenever the baud rate changes. At low
baud rates (19.2kbps and below) the timeout is the number of bits in 2
characters. At higher speed it's calculated to be 500 microseconds
worth of bits. The idea is to compromise between being responsive in
interactive situations and not timing out prematurely during a brief
pause in bulk data flow. The old fixed timeout of 1.5 characters was
just 32 microseconds at 460kbps.
At interrupt time, check for receiver holding register overrun status
and set the corresponding status bit in the return value.
When handling a buffer overrun, get a single buffer emptied and handed
back to the hardware as quickly as possible, then deal with the second
buffer. This at least minimizes data loss compared to the old logic
that fully processed both buffers before restarting the hardware.
Rewrite the logic for handling buffers after a receive timeout. The
original author speculated in a comment that there may be a race with
high speed data. There was, although it was rare. The code now handles
all three possible scenarios on receive timeout: two empty buffers, one
empty and one partial buffer, or one full and one partial buffer.
Reviewed by: imp
add the ability for userland to be notified of changes on gpio pins via
a select(2)/read(2) interface.
Change the interrupt handler from filtered to threaded.
Because of the uiomove() calls in the new interface, change locking from
standard mutex to sx.
Add / restore the at91_gpio_high_z() function.
Reviewed by: imp (long ago)
of bits, not just a 0/1 indicating whether any of the masked bits are on.
This is compatible with the single in-tree caller of this function right now
(at91_vbus_poll() in dev/usb/controller/at91dci_atemelarm.c).
With some recent busdma refactoring, sometimes it happens that a sync
op gets called when bus_dmamap_load() never got called, which results
in a spurious warning about a map mismatch when no sync operations will
actually happen anyway. Now the check is done only if a sync operation
is actually performed, and the result of the check is a panic, not just
a printf.
Reviewed by: cognet (who prevented me from donning a point hat)
original 2us are indeed not enough, 3us are working quite well on my tests.
To be more safe set minimal period to 5us and to be even more safe replicate
here from HPET mechanism of rereading counter after programming comparator.
This change allows to handle 30K of short nanosleep() calls per second on
Raspberry Pi instead of just 8K before.
Discussed with: gonzo
do not map the b_pages pages into buffer_map KVA. The use of the
unmapped buffers eliminate the need to perform TLB shootdown for
mapping on the buffer creation and reuse, greatly reducing the amount
of IPIs for shootdown on big-SMP machines and eliminating up to 25-30%
of the system time on i/o intensive workloads.
The unmapped buffer should be explicitely requested by the GB_UNMAPPED
flag by the consumer. For unmapped buffer, no KVA reservation is
performed at all. The consumer might request unmapped buffer which
does have a KVA reserve, to manually map it without recursing into
buffer cache and blocking, with the GB_KVAALLOC flag.
When the mapped buffer is requested and unmapped buffer already
exists, the cache performs an upgrade, possibly reusing the KVA
reservation.
Unmapped buffer is translated into unmapped bio in g_vfs_strategy().
Unmapped bio carry a pointer to the vm_page_t array, offset and length
instead of the data pointer. The provider which processes the bio
should explicitely specify a readiness to accept unmapped bio,
otherwise g_down geom thread performs the transient upgrade of the bio
request by mapping the pages into the new bio_transient_map KVA
submap.
The bio_transient_map submap claims up to 10% of the buffer map, and
the total buffer_map + bio_transient_map KVA usage stays the
same. Still, it could be manually tuned by kern.bio_transient_maxcnt
tunable, in the units of the transient mappings. Eventually, the
bio_transient_map could be removed after all geom classes and drivers
can accept unmapped i/o requests.
Unmapped support can be turned off by the vfs.unmapped_buf_allowed
tunable, disabling which makes the buffer (or cluster) creation
requests to ignore GB_UNMAPPED and GB_KVAALLOC flags. Unmapped
buffers are only enabled by default on the architectures where
pmap_copy_page() was implemented and tested.
In the rework, filesystem metadata is not the subject to maxbufspace
limit anymore. Since the metadata buffers are always mapped, the
buffers still have to fit into the buffer map, which provides a
reasonable (but practically unreachable) upper bound on it. The
non-metadata buffer allocations, both mapped and unmapped, is
accounted against maxbufspace, as before. Effectively, this means that
the maxbufspace is forced on mapped and unmapped buffers separately.
The pre-patch bufspace limiting code did not worked, because
buffer_map fragmentation does not allow the limit to be reached.
By Jeff Roberson request, the getnewbuf() function was split into
smaller single-purpose functions.
Sponsored by: The FreeBSD Foundation
Discussed with: jeff (previous version)
Tested by: pho, scottl (previous version), jhb, bf
MFC after: 2 weeks
register from a bus space resource.
Note that this macro is just for ARM, and is intended to have a short
lifespan. The DMA engines in some SoCs need the physical address of a
memory-mapped device register as one of the arguments for the transfer.
Several scattered ad-hoc solutions have been converted to use this macro,
which now also serves to mark the places where a more complete fix needs
to be applied (after that fix has been designed).
pages around, taking array of vm_page_t both for source and
destination. Starting offsets and total transfer size are specified.
The function implements optimal algorithm for copying using the
platform-specific optimizations. For instance, on the architectures
were the direct map is available, no transient mappings are created,
for i386 the per-cpu ephemeral page frame is used. The code was
typically borrowed from the pmap_copy_page() for the same
architecture.
Only i386/amd64, powerpc aim and arm/arm-v6 implementations were
tested at the time of commit. High-level code, not committed yet to
the tree, ensures that the use of the function is only allowed after
explicit enablement.
For sparc64, the existing code has known issues and a stab is added
instead, to allow the kernel linking.
Sponsored by: The FreeBSD Foundation
Tested by: pho (i386, amd64), scottl (amd64), ian (arm and arm-v6)
MFC after: 2 weeks
and that can drive someone crazy. While m_get2() is young and not
documented yet, change its order of arguments to match m_getm2().
Sorry for churn, but better now than later.
when the kernel attempts to unwind through this function.
The .fnstart and .fnend in this function should be moved to macros but we
are currently missing an END macro on ARM.
future further optimizations where the vm_object lock will be held
in read mode most of the time the page cache resident pool of pages
are accessed for reading purposes.
The change is mostly mechanical but few notes are reported:
* The KPI changes as follow:
- VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK()
- VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK()
- VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK()
- VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED()
(in order to avoid visibility of implementation details)
- The read-mode operations are added:
VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(),
VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED()
* The vm/vm_pager.h namespace pollution avoidance (forcing requiring
sys/mutex.h in consumers directly to cater its inlining functions
using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h
consumers now must include also sys/rwlock.h.
* zfs requires a quite convoluted fix to include FreeBSD rwlocks into
the compat layer because the name clash between FreeBSD and solaris
versions must be avoided.
At this purpose zfs redefines the vm_object locking functions
directly, isolating the FreeBSD components in specific compat stubs.
The KPI results heavilly broken by this commit. Thirdy part ports must
be updated accordingly (I can think off-hand of VirtualBox, for example).
Sponsored by: EMC / Isilon storage division
Reviewed by: jeff
Reviewed by: pjd (ZFS specific review)
Discussed with: alc
Tested by: pho
other architectures [1].
While here:
- Remove an unused and commented out include.
- Add a comment describing the file that other copies have.
- Fix the style of the defines and add a comment on what each one is.
Suggested by: [1] alc
sent a SIGABRT when it is loaded as it is too large. This is the smallest
power of two MiB value that allows us to execute clang.
While here wrap it in an #ifndef to be consistent with the other
architectures.
Submitted by: Daisuke Aoyama <aoyama at peach.ne.jp>
