1. Rise is recognized in identdcpu.c.
2. The TSC is not written to. A workaround for the CPU bug is being
applied to clock.c (the bug being that the mP6 has TSC enabled
in its CPUID-capabilities, but it only supports reading it. If we
try to write to it (MSR 16), a GPF occurs.) The new behavior is that
FreeBSD will _not_ zero the TSC. Instead, we do a bit of 64-bit
arithmetic.
Reviewed by: msmith
Obtained from: unfurl & msmith
The old version only worked right when the time was read strictly
more often than every 1/HZ seconds, but we only guarantee reading
it every (1/HZ + epsilon) seconds. Part of rev.1.126-1.127 attempted
to fix this but didn't succeed. Detect counter rollover using the
heuristic from the old version of microtime() with additional
complications for supporting calls from fast interrupt handlers.
This works provided i8254 interrupts are not delayed by more than
1/(2*HZ) seconds.
This needs more comments, and cleanups for the SMP case, and more
testing of the SMP case before it is merged into RELENG_3.
Tested by: jhay
Interrupts under the new scheme are managed by the i386 nexus with the
awareness of the resource manager. There is further room for optimizing
the interfaces still. All the users of register_intr()/intr_create()
should be gone, with the exception of pcic and i386/isa/clock.c.
went backwards when interrupts were masked for more than one i8254
interrupt period. It sometimes went backwards when the i8254 counter
was reprogrammed. Neither of these should happen in normal operation.
Update the i8254 timecounter support variables atomically. Calling
timecounter functions from fast interrupt handlers may actually work
in all cases now.
and use this when masking/unmasking interrupts.
Maintain a mapping from (iopaic number, int pin) tuple to irq number,
and use this when configuring devices and programming the ioapics.
Previous code assumed that irq number was equal to int pin number, and
that the ioapic number was 0.
Don't let an AP enter _cpu_switch before all local apics are initialized.
Clean up (or if antipodic: down) some of the msgbuf stuff.
Use an inline function rather than a macro for timecounter delta.
Maintain process "on-cpu" time as 64 bits of microseconds to avoid
needless second rollover overhead.
Avoid calling microuptime the second time in mi_switch() if we do
not pass through _idle in cpu_switch()
This should reduce our context-switch overhead a bit, in particular
on pre-P5 and SMP systems.
WARNING: Programs which muck about with struct proc in userland
will have to be fixed.
Reviewed, but found imperfect by: bde
"time" wasn't a atomic variable, so splfoo() protection were needed
around any access to it, unless you just wanted the seconds part.
Most uses of time.tv_sec now uses the new variable time_second instead.
gettime() changed to getmicrotime(0.
Remove a couple of unneeded splfoo() protections, the new getmicrotime()
is atomic, (until Bruce sets a breakpoint in it).
A couple of places needed random data, so use read_random() instead
of mucking about with time which isn't random.
Add a new nfs_curusec() function.
Mark a couple of bogosities involving the now disappeard time variable.
Update ffs_update() to avoid the weird "== &time" checks, by fixing the
one remaining call that passwd &time as args.
Change profiling in ncr.c to use ticks instead of time. Resolution is
the same.
Add new function "tvtohz()" to avoid the bogus "splfoo(), add time, call
hzto() which subtracts time" sequences.
Reviewed by: bde
on the IOAPIC being connected to the 8254 timer interrupt.
Verify that timer interrupts are delivered. If they aren't, attempt
a fallback to mixed mode (i.e. routing the timer interrupt via the 8259 PIC).
it runs at a constant frequency. This was less of an issue before,
because the TSC only interpolated in the HZ intervals, but now where
the timecounter is used all the way, this becomes much more visible.
Nit: Fix a printf which triggered the bde-filter.
Highlights:
* Simple model for underlying hardware.
* Hardware basis for timekeeping can be changed on the fly.
* Only one hardware clock responsible for TOD keeping.
* Provides a real nanotime() function.
* Time granularity: .232E-18 seconds.
* Frequency granularity: .238E-12 s/s
* Frequency adjustment is continuous in time.
* Less overhead for frequency adjustment.
* Improves xntpd performance.
Reviewed by: bde, bde, bde
is "acquired". This fixes a TSC biasing error of about 10 msec when
pcaudio is active.
Update `time' before calling hardclock() when timer0 is being released.
This is not known to be important.
Added some delays in writertc(). Efficiency is not critical here, unlike
in rtcin(), and we already use conservative delays there.
Don't touch the hardware when machdep.i8254_freq is being changed but
the maximum count wouldn't change. This fixes jitter of up to 10 msec
for most small adjustments to machdep.i8254_freq. When the maximum
count needs to change, the hardware should be adjusted more carefully.
in <machine/cpu.h>. Moved the declarations to <machine/cputypes.h>.
Fixed style bugs in the moved code. Fixed everything that depended on
the nested include. Don't include <machine/cpu.h> (in the changed files)
unless something in it is used directly.
Add a simplelock to deal with disable_intr()/enable_intr() as used in UP kernel.
UP kernel expects that this is enough to guarantee exclusive access to
regions of code bracketed by these 2 functions.
Add a simplelock to bracket clock accesses in clock.c: clock_lock.
Help from: Bruce Evans <bde@zeta.org.au>
Made NEW_STRATEGY default.
Removed misc. old cruft.
Centralized simple locks into mp_machdep.c
Centralized simple lock macros into param.h
More cleanup in the direction of making splxx()/cpl MP-safe.
- removed TEST_ALTTIMER.
- removed APIC_PIN0_TIMER.
- removed TIMER_ALL.
apic_vector.s:
- new algorithm where a CPU uses try_mplock instead of get_mplock:
if successful continue as before.
if fail set ipending bit, mask INT (to avoid recursion), cleanup & iret.
This allows the CPU to return to successful work, while the ISR will be run
by the CPU holding the lock as part of the doreti dance.
simplifies some assumptions and stops some code compile problems.
This should fix the compile hiccup in PR#3491, but smp kernel profiling
isn't likely to be fixed by this.
There are various options documented in i386/conf/LINT, there is more to
come over the next few days.
The kernel should run pretty much "as before" without the options to
activate SMP mode.
There are a handful of known "loose ends" that need to be fixed, but
have been put off since the SMP kernel is in a moderately good condition
at the moment.
This commit is the result of the tinkering and testing over the last 14
months by many people. A special thanks to Steve Passe for implementing
the APIC code!
I have code to calibrate the overhead fairly accurately, but there
is little point in using it since it is most accurate on machines
where an estimate of 0 works well. On slow machines, the accuracy
of DELAY() has a large variance since it is limited by the resolution
of getit() even if the initial delay is calibrated perfectly.
Use fixed point and long longs to speed up scaling in DELAY().
The old method slowed down a lot when the frequency became variable.
Assume the default frequency for short delays so that the fixed
point calculation can be exact.
Fast scaling is only important for small delays. Scaling is done
after looking at the counter and outside the loop, so it doesn't
decrease accuracy or resolution provided it completes before the
delay is up. The comment in the code is still confused about this.
called early for console i/o. The timer is usually in BIOS mode
if it isn't explicitly initialized. Then it counts twice as fast
and has a max count of 65535 instead of 11932. The larger count
tended to cause infinite loops for delays of > 20 us. Such delays
are rare. For syscons and kbdio, DELAY() is only called early
enough to matter for ddb input after booting with -d, and the delay
is too small to matter (and too small to be correct) except in the
PC98 case. For pcvt, DELAY() is not used for small delays (pcvt
uses its own broken routine instead of the standard broken one),
but some versions call DELAY() with a large arg when they unnecessarily
initialize the keyboard for doing console output. The problem is
more serious for pcvt because there is always some early console
output.
Guard against the i8254 timer being partially or incorrectly
initialized. This would have prevented the endless loop.
Should be in 2.2.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
instead of 0 if there is no input.
syscons.c:
Added missing spl locking in sccncheckc(). Return the same value as
sccngetc() would. It is wrong for sccngetc() to return non-ASCII, but
stripping the non-ASCII bits doesn't help.
make it more intelligible, improve the partially bogus locking, and
allow for a ``quick re-acquiration'' from a pending release of timer 0
that happened ``recently'', so it was not processed yet by clkintr().
This latter modification now finally allows to play XBoing over
pcaudio without losing sounds or getting complaints. ;-) (XBoing
opens/writes/closes the sound device all over the day.)
Correct locking for sysbeep().
Extensively (:-) reviewed by: bde
Testing with the high frequency of 20000 Hz (to find problems) only found
the problem that this frequency is too high for slow i386's.
Disable interrupts while setting the timer frequency. This was unnecessary
before rev.1.57 and forgotten in rev.1.57. The critical (i8254) interrupts
are disabled in another way at boot time but not in the sysctl to change
the frequency.
enable flag instead of enable_intr() to restore it to its usual state.
getit() is only called from DELAY() so there is no point in optimising
its speed (this wasn't so clear when it was extern), and using
enable_intr() made it inconvenient to call DELAY() from probes that need
to run with interrupts disabled.
time. The results are currently ignored unless certain temporary options
are used.
Added sysctls to support reading and writing the clock frequency variables
(not the frequencies themselves). Writing is supposed to atomically
adjust all related variables.
machdep.c:
Fixed spelling of a function name in a comment so that I can log this
message which should have been with the previous commit.
Initialize `cpu_class' earlier so that it can be used in startrtclock()
instead of in calibrate_cyclecounter() (which no longer exists).
Removed range checking of `cpu'. It is always initialized to CPU_XXX
so it is less likely to be out of bounds than most variables.
clock.h:
Removed I586_CYCLECTR(). Use rdtsc() instead.
clock.c:
TIMER_FREQ is now a variable timer_freq that defaults to the old value of
TIMER_FREQ. #define'ing TIMER_FREQ should still work and may be the best
way of setting the frequency.
Calibration involves counting cycles while watching the RTC for one second.
This gives values correct to within (a few ppm) + (the innaccuracy of the
RTC) on my systems.
regarding apm to LINT
- Disabled the statistics clock on machines which have an APM BIOS and
have the options "APM_BROKEN_STATCLOCK" enabled (which is default
in GENERIC now)
- move around some of the code in clock.c dealing with the rtc to make
it more obvios the effects of disabling the statistics clock
Reviewed by: bde
Always delay using one inb(0x84) after each i/o in rtcin() - don't
do this conditional on the bogus option DUMMY_NOPS not being defined.
If you want an optionally slightly faster rtcin() again, then inline
it and use a better named option or sysctl variable. It only needs
to be fast in rtcintr().
clock interrupts.
Keep a 1-in-16 smoothed average of the length of each tick. If the
CPU speed is correctly diagnosed, this should give experienced users
enough information to figure out a more suitable value for `tick'.
variants, idea taken from NetBSD clock.c.
At least year calculation was wrong, pointed by Bruce.
Use different strategy to store year for BIOS without RTC_CENTURY
- Don't print out meaningless iCOMP numbers, those are for droids.
- Use a shorter wait to determine clock rate to avoid deficiencies
in DELAY().
- Use a fixed-point representation with 8 bits of fraction to store
the rate and rationalize the variable name. It would be
possible to use even more fraction if it turns out to be
worthwhile (I rather doubt it).
The question of source code arrangement remains unaddressed.
