what Linux does. This is because robust futexes are mostly
userspace thing which we cannot alter. Two syscalls maintain
pointer to userspace list and when process exits a routine
walks this list waking up processes sleeping on futexes
from that list.
Reviewed by: kib (mentor)
MFC after: 1 month
from idle over the next tick.
- Add a new MD routine, cpu_wake_idle() to wakeup idle threads who are
suspended in cpu specific states. This function can fail and cause the
scheduler to fall back to another mechanism (ipi).
- Implement support for mwait in cpu_idle() on i386/amd64 machines that
support it. mwait is a higher performance way to synchronize cpus
as compared to hlt & ipis.
- Allow selecting the idle routine by name via sysctl machdep.idle. This
replaces machdep.cpu_idle_hlt. Only idle routines supported by the
current machine are permitted.
Sponsored by: Nokia
for better structure.
Much of this is related to <sys/clock.h>, which should really have
been called <sys/calendar.h>, but unless and until we need the name,
the repocopy can wait.
In general the kernel does not know about minutes, hours, days,
timezones, daylight savings time, leap-years and such. All that
is theoretically a matter for userland only.
Parts of kernel code does however care: badly designed filesystems
store timestamps in local time and RTC chips almost universally
track time in a YY-MM-DD HH:MM:SS format, and sometimes in local
timezone instead of UTC. For this we have <sys/clock.h>
<sys/time.h> on the other hand, deals with time_t, timeval, timespec
and so on. These know only seconds and fractions thereof.
Move inittodr() and resettodr() prototypes to <sys/time.h>.
Retain the names as it is one of the few surviving PDP/VAX references.
Move startrtclock() to <machine/clock.h> on relevant platforms, it
is a MD call between machdep.c/clock.c. Remove references to it
elsewhere.
Remove a lot of unnecessary <sys/clock.h> includes.
Move the machdep.disable_rtc_set sysctl to subr_rtc.c where it belongs.
XXX: should be kern.disable_rtc_set really, it's not MD.
Note this includes changes to all drivers and moves some device firmware
loading to use firmware(9) and a separate module (e.g. ral). Also there
no longer are separate wlan_scan* modules; this functionality is now
bundled into the wlan module.
Supported by: Hobnob and Marvell
Reviewed by: many
Obtained from: Atheros (some bits)
noise from sio per unit. sio likes to probe if interrupts are configured
correctly by looking at the pending bits of the atpic in order to put a
non-fatal warning on the console. I think I'd rather read the pending
bits from the apics, but I'm not sure its worth the hassle.
lookup hard interrupt events by number. Ignore the irq# for soft intrs.
- Add support to cpuset for binding hardware interrupts. This has the
side effect of binding any ithread associated with the hard interrupt.
As per restrictions imposed by MD code we can only bind interrupts to
a single cpu presently. Interrupts can be 'unbound' by binding them
to all cpus.
Reviewed by: jhb
Sponsored by: Nokia
2/4MB page from a PDE. Specifically, change it to use PG_PS_FRAME,
not PG_FRAME, to extract the physical address of a 2/4MB page from a
PDE.
Change the last argument passed to pmap_pv_insert_pde() from a
vm_page_t representing the first 4KB page of a 2/4MB page to the
vm_paddr_t of the 2/4MB page. This avoids an otherwise unnecessary
conversion from a vm_paddr_t to a vm_page_t in pmap_copy().
allows all the INTR_FILTER #ifdef's to be removed from the MD interrupt
code.
- Rename the intr_event 'eoi', 'disable', and 'enable' hooks to
'post_filter', 'pre_ithread', and 'post_ithread' to be less x86-centric.
Also, add a comment describe what the MI code expects them to do.
- On amd64, i386, and powerpc this is effectively a NOP.
- On arm, don't bother masking the interrupt unless the ithread is
scheduled in the non-INTR_FILTER case to match what INTR_FILTER did.
Also, don't bother unmasking the interrupt in the post_filter case if
we never masked it. The INTR_FILTER case had been doing this by having
arm_unmask_irq for the post_filter (formerly 'eoi') hook.
- On ia64, stray interrupts are now masked for the non-INTR_FILTER case.
They were already masked in the INTR_FILTER case.
- On sparc64, use the a NULL pre_ithread hook and use intr_enable_eoi() for
both the 'post_filter' and 'post_ithread' hooks to match what the
non-INTR_FILTER code did.
- On sun4v, retire the ithread wrapper hack by using an appropriate
'post_ithread' hook instead (it's what 'post_ithread'/'enable' was
designed to do even in 5.x).
Glanced at by: piso
Reviewed by: marius
Requested by: marius [1], [5]
Tested on: amd64, i386, arm, sparc64
given pmap is never NULL, and therefore pmap_pml4e() can never return
NULL. The pervasive use of these inline functions throughout the pmap
makes these simple changes worthwhile.
to detect (or load) kernel NLM support in rpc.lockd. Remove the '-k'
option to rpc.lockd and make kernel NLM the default. A user can still
force the use of the old user NLM by building a kernel without NFSLOCKD
and/or removing the nfslockd.ko module.
frequency generation and what frequency the generated was anyones
guess.
In general the 32.768kHz RTC clock x-tal was the best, because that
was a regular wrist-watch Xtal, whereas the X-tal generating the
ISA bus frequency was much lower quality, often costing as much as
several cents a piece, so it made good sense to check the ISA bus
frequency against the RTC clock.
The other relevant property of those machines, is that they
typically had no more than 16MB RAM.
These days, CPU chips croak if their clocks are not tightly within
specs and all necessary frequencies are derived from the master
crystal by means if PLL's.
Considering that it takes on average 1.5 second to calibrate the
frequency of the i8254 counter, that more likely than not, we will
not actually use the result of the calibration, and as the final
clincher, we seldom use the i8254 for anything besides BEL in
syscons anyway, it has become time to drop the calibration code.
If you need to tell the system what frequency your i8254 runs,
you can do so from the loader using hw.i8254.freq or using the
sysctl kern.timecounter.tc.i8254.frequency.
these days, so de-generalize the acquire_timer/release_timer api
to just deal with speakers.
The new (optional) MD functions are:
timer_spkr_acquire()
timer_spkr_release()
and
timer_spkr_setfreq()
the last of which configures the timer to generate a tone of a given
frequency, in Hz instead of 1/1193182th of seconds.
Drop entirely timer2 on pc98, it is not used anywhere at all.
Move sysbeep() to kern/tty_cons.c and use the timer_spkr*() if
they exist, and do nothing otherwise.
Remove prototypes and empty acquire-/release-timer() and sysbeep()
functions from the non-beeping archs.
This eliminate the need for the speaker driver to know about
i8254frequency at all. In theory this makes the speaker driver MI,
contingent on the timer_spkr_*() functions existing but the driver
does not know this yet and still attaches to the ISA bus.
Syscons is more tricky, in one function, sc_tone(), it knows the hz
and things are just fine.
In the other function, sc_bell() it seems to get the period from
the KDMKTONE ioctl in terms if 1/1193182th second, so we hardcode
the 1193182 and leave it at that. It's probably not important.
Change a few other sysbeep() uses which obviously knew that the
argument was in terms of i8254 frequency, and leave alone those
that look like people thought sysbeep() took frequency in hertz.
This eliminates the knowledge of i8254_freq from all but the actual
clock.c code and the prof_machdep.c on amd64 and i386, where I think
it would be smart to ask for help from the timecounters anyway [TBD].
are mixed. Some pure context switch microbenchmarks show up to 29%
improvement. Pipe based context switch microbenchmarks show up to 7%
improvement. Real world tests are far less impressive as they are
dominated more by actual work than switch overheads, but depending on
the machine in question, workload, kernel options, phase of moon, etc, a
few percent gain might be seen.
Summary of changes:
- don't reload MSR_[FG]SBASE registers when context switching between
non-threaded userland apps. These typically cost 120 clock cycles each
on an AMD cpu (less on Barcelona/Phenom). Intel cores are probably no
faster on this.
- The above change only helps unthreaded userland apps that tend to use
the same value for gsbase. Threaded apps will get no benefit from this.
- reorder things like accessing the pcb to be in memory order, to give
prefetching a better chance of working. Operations are now in increasing
memory address order, rather than reverse or random.
- Push some lesser used code out of the main code paths. Hopefully
allowing better code density in cache lines. This is probably futile.
- (part 2 of previous item) Reorder code so that branches have a more
realistic static branch prediction hint. Both Intel and AMD cpus
default to predicting branches to lower memory addresses as being
taken, and to higher memory addresses as not being taken. This is
overridden by the limited dynamic branch prediction subsystem. A trip
through userland might overflow this.
- Futule attempt at spreading the use of the results of previous operations
in new operations. Hopefully this will allow the cpus to execute in
parallel better.
- stop wasting 16 bytes at the top of kernel stack, below the PCB.
- Never load the userland fs/gsbase registers for kthreads, but preserve
curpcb->pcb_[fg]sbase as caches for the cpu. (Thanks Jeff!)
Microbenchmarking this code seems to be really sensitive to things like
scheduling luck, timing, cache behavior, tlb behavior, kernel options,
other random code changes, etc.
While it doesn't help heavy userland workloads much, it does help high
context switch loads a little, and should help those that involve
switching via kthreads a bit more.
A special thanks to Kris for the testing and reality checks, and Jeff for
tormenting me into doing this. :)
This is still work-in-progress.
PTE if that PTE has the PG_RW bit set. However, this assumption does
not hold on recent processors from Intel. For example, consider a PTE
that has the PG_RW bit set but the PG_M bit clear. Suppose this PTE
is cached in the TLB and later the PG_RW bit is cleared in the PTE,
but the corresponding TLB entry is not (yet) invalidated.
Historically, upon a write access using this (stale) TLB entry, the
TLB would observe that the PG_RW bit had been cleared and initiate a
page fault, aborting the setting of the PG_M bit in the PTE. Now,
however, P4- and Core2-family processors will set the PG_M bit before
observing that the PG_RW bit is clear and initiating a page fault. In
other words, the write does not occur but the PG_M bit is still set.
The real impact of this difference is not that great. Specifically,
we should no longer assert that any PTE with the PG_M bit set must
also have the PG_RW bit set, and we should ignore the state of the
PG_M bit unless the PG_RW bit is set. However, these changes enable
me to remove a work-around from pmap_promote_pde(), the superpage
promotion procedure.
(Note: The AMD processors that we have tested, including the latest,
the Phenom, still exhibit the historical behavior.)
Acknowledgments: After I observed the problem, Stephan (ups) was
instrumental in characterizing the exact behavior of Intel's recent
TLBs.
Tested by: Peter Holm
The overflow causes the wraparound with consequent corruption of the
(almost) whole address space mapping.
As Alan noted, pmap_copy() does not require the wrap-around checks
because it cannot be applied to the kernel's pmap. The checks there are
included for consistency.
Reported and tested by: kris (i386/pmap.c:pmap_remove() part)
Reviewed by: alc
MFC after: 1 week
lock in the 8259A drivers as these drivers are only used on UP systems.
This slightly reduces the penalty of an SMP kernel (such as GENERIC) on
a UP x86 machine.
resource to a CPU. The default method is to pass the request up to the
parent similar to BUS_CONFIG_INTR() so that all busses don't have to
explicitly implement bus_bind_intr. A bus_bind_intr(9) wrapper routine
similar to bus_setup/teardown_intr() is added for device drivers to use.
Unbinding an interrupt is done by binding it to NOCPU. The IRQ resource
must be allocated, but it can happen in any order with respect to
bus_setup_intr(). Currently it is only supported on amd64 and i386 via
nexus(4) methods that simply call the intr_bind() routine.
Tested by: gallatin
- Always include the ie_disable and ie_eoi methods in 'struct intr_event'
and collapse down to one intr_event_create() routine. The disable and
eoi hooks simply aren't used currently in the !INTR_FILTER case.
- Expand 'disab' to 'disable' in a few places.
- Use function casts for arm and i386:intr_eoi_src() instead of wrapper
routines since to trim one extra indirection.
Compiled on: {arm,amd64,i386,ia64,ppc,sparc64} x {FILTER, !FILTER}
Tested on: {amd64,i386} x {FILTER, !FILTER}
