- Avoid side-effect assignments in if statements when possible.
- Don't use ! to check for NULL pointers, explicitly check against NULL.
- Explicitly check error return values against 0.
- Don't use INTR_MPSAFE for interrupt handlers with only filters as it is
meaningless.
- Remove unneeded function casts.
looking to see if there is an existing IRQ resource for a given IRQ
provided by the BIOS and using that RID if so. Otherwise, allocate a new
RID for the new IRQ.
Reviewed by: mav (a while ago)
number of unexplained interrupt problems. For some reason, using HPET
interrupts there breaks HDA sound. Legacy route mode interrupts reported
to work fine there.
The main goal of this is to generate timer interrupts only when there is
some work to do. When CPU is busy interrupts are generating at full rate
of hz + stathz to fullfill scheduler and timekeeping requirements. But
when CPU is idle, only minimum set of interrupts (down to 8 interrupts per
second per CPU now), needed to handle scheduled callouts is executed.
This allows significantly increase idle CPU sleep time, increasing effect
of static power-saving technologies. Also it should reduce host CPU load
on virtualized systems, when guest system is idle.
There is set of tunables, also available as writable sysctls, allowing to
control wanted event timer subsystem behavior:
kern.eventtimer.timer - allows to choose event timer hardware to use.
On x86 there is up to 4 different kinds of timers. Depending on whether
chosen timer is per-CPU, behavior of other options slightly differs.
kern.eventtimer.periodic - allows to choose periodic and one-shot
operation mode. In periodic mode, current timer hardware taken as the only
source of time for time events. This mode is quite alike to previous kernel
behavior. One-shot mode instead uses currently selected time counter
hardware to schedule all needed events one by one and program timer to
generate interrupt exactly in specified time. Default value depends of
chosen timer capabilities, but one-shot mode is preferred, until other is
forced by user or hardware.
kern.eventtimer.singlemul - in periodic mode specifies how much times
higher timer frequency should be, to not strictly alias hardclock() and
statclock() events. Default values are 2 and 4, but could be reduced to 1
if extra interrupts are unwanted.
kern.eventtimer.idletick - makes each CPU to receive every timer interrupt
independently of whether they busy or not. By default this options is
disabled. If chosen timer is per-CPU and runs in periodic mode, this option
has no effect - all interrupts are generating.
As soon as this patch modifies cpu_idle() on some platforms, I have also
refactored one on x86. Now it makes use of MONITOR/MWAIT instrunctions
(if supported) under high sleep/wakeup rate, as fast alternative to other
methods. It allows SMP scheduler to wake up sleeping CPUs much faster
without using IPI, significantly increasing performance on some highly
task-switching loads.
Tested by: many (on i386, amd64, sparc64 and powerc)
H/W donated by: Gheorghe Ardelean
Sponsored by: iXsystems, Inc.
are still bound to BSP. It confuses timer management logic in per-CPU mode
and may cause timer not being reloaded. Check such cases on interrupt
arival and reload timer to give system some more time to manage proper
binding.
- Add special check for case when time expires before being programmed.
This fixes interrupt loss and respectively timer death on attempt to
program very short interval. Increase minimal supported period to more
realistic value.
- Add support for hint.hpet.X.allowed_irqs tunable, allowing manually
specify which interrupts driver allowed to use. Unluckily, many BIOSes
program wrong allowed interrupts mask, so driver tries to stay on safe
side by not using unshareable ISA IRQs. This option gives control over
this limitation, allowing more per-CPU timers to be provided, when FSB
interrupts are not supported. Value of this tunable is bitmask.
- Do not use regular interrupts on virtual machines. QEMU and VirtualBox
do not support them properly, that may cause problems. Stay safe by default.
Same time both QEMU and VirtualBox work fine in legacy_route mode.
VirtualBox also works fine if manually specify allowed ISA IRQs with above.
lengths. Make MI wrapper code to validate periods in request. Make kernel
clock management code to honor these hardware limitations while choosing hz,
stathz and profhz values.
HPET to steal IRQ0 from i8254 and IRQ8 from RTC timers. It can be suitable
for HPETs without FSB interrupts support, as it gives them two unshared
IRQs. It allows them to provide one per-CPU event timer on dual-CPU system,
that should be suitable for further tickless kernels.
To enable it, such lines may be added to /boot/loader.conf:
hint.atrtc.0.clock=0
hint.attimer.0.clock=0
hint.hpet.0.legacy_route=1
writing event timer drivers, for choosing best possible drivers by machine
independent code and for operating them to supply kernel with hardclock(),
statclock() and profclock() events in unified fashion on various hardware.
Infrastructure provides support for both per-CPU (independent for every CPU
core) and global timers in periodic and one-shot modes. MI management code
at this moment uses only periodic mode, but one-shot mode use planned for
later, as part of tickless kernel project.
For this moment infrastructure used on i386 and amd64 architectures. Other
archs are welcome to follow, while their current operation should not be
affected.
This patch updates existing drivers (i8254, RTC and LAPIC) for the new
order, and adds event timers support into the HPET driver. These drivers
have different capabilities:
LAPIC - per-CPU timer, supports periodic and one-shot operation, may
freeze in C3 state, calibrated on first use, so may be not exactly precise.
HPET - depending on hardware can work as per-CPU or global, supports
periodic and one-shot operation, usually provides several event timers.
i8254 - global, limited to periodic mode, because same hardware used also
as time counter.
RTC - global, supports only periodic mode, set of frequencies in Hz
limited by powers of 2.
Depending on hardware capabilities, drivers preferred in following orders,
either LAPIC, HPETs, i8254, RTC or HPETs, LAPIC, i8254, RTC.
User may explicitly specify wanted timers via loader tunables or sysctls:
kern.eventtimer.timer1 and kern.eventtimer.timer2.
If requested driver is unavailable or unoperational, system will try to
replace it. If no more timers available or "NONE" specified for second,
system will operate using only one timer, multiplying it's frequency by few
times and uing respective dividers to honor hz, stathz and profhz values,
set during initial setup.
device, make sure we have no real HPET device entry with same ID.
As side effect, it potentially allows several HPETs to be attached.
Use first of them for timecounting, rest (if ever present) could later
be used as event sources.
Also, account for a quirk of AMD/ATI HPET which reports number of timers
instead of id of the last timer as manadated by the specification.
Currently this has no effect on functionality but in the future we may
make actual use of the HPET timers, not only of its timecounter.
MFC after: 2 weeks
o acpi_hpet: auto-added 'wildcard' devices can be identified by
non-NULL handle attribute.
o acpi_ec: auto-add 'wildcard' devices can be identified by
unset (NULL) private attribute.
o acpi_cpu: use private instead of magic to store cpu id.
Reviewed by: jhb
Silence from: acpi@
MFC after: 2 weeks
X-MFC-Note: perhaps the ivar should stay for ABI stability
spec:
- Use read/modify/write cycles to enable and disable the HPET instead of
writing 0 to reserved bits.
- Shutdown the HPET during suspend as encouraged by the spec.
- Fail to attach to an HPET with a period of zero.
MFC after: 1 week
PR: kern/119675 [3]
Reported by: Leo Bicknell | bicknell ufp.org
of directly from acpi0. Before it would attach prior to the sysresource
devices, causing the later allocation of its memory range to fail and
print a warning like "acpi0: reservation of fed00000, 1000 (3) failed".
Use an explicit define for our probe order base value of 10.
Help from: jhb
Tested by: Abdullah Ibn Hamad Al-Marri <almarrie / gmail.com>
MFC after: 3 days
Approved by: re
the fast or safe/slow method is in use. Fast remains at 1000, slow is
now at 850 (always preferred to TSC). Since the HPET has proven slower
than ACPI-fast on some systems, drop its quality to 900. In the future,
it is hoped that HPET performance will improve as it is the main
timer Intel supports. HPET may move back to 2000 in -current once RELENG_7
is branched to ensure that it gets tested.
Approved by: re
advancing. Read from the timer before attaching to be sure it advances
in 1 us. Since the slowest rate allowed by the spec is 10 MHz, the
timer is guaranteed to change in this interval if it is working.
Tested by: Rui Paulo
Approved by: re
MFC after: 3 days
Move the code for printing timer statistics into a test function instead of
an ifdef (accessible via the debug.acpi.hpet_test tunable). Also use defines
for register offsets instead of magic values.
Courtesy of: slow flight to HK
