Part of a previous change introduced logice which used the throttling
execution rate calibrated value to determine clock calibration when
throttling is enabled. This provides significantly worse results than the
normal self correcting calibration process. This commit reverses that
part of the previous change.
Added debug CHECK option to the sim_timer_activate_after() to verify
that coscheduled events actually have sim_activate_time_usecs() results
which are consistent with each other.
Additionally, coschedule tick processing now properly counts down
pending coschedule queued activities.
- Add support to query remaining usecs on pending events.
- Generalized the sim_interval adjustment in sim_idle to allow more than
a single decrement.
- More overhead reduction when idling.
- Carry usec values as double through out to fully support long wall clock
delays.
- Support for arbitrary long wait intervals in sim_activate_after with
precisely correct delays aligned with the calibrated clock once
per second.
- Proper handling of calls to sim_cancel for calibrated timer units
- Properly allow stopping of calibrated clock by calling sim_rtcn_calb
with a ticksper == 0
- Only schedule asynchronous timer activities for delays longer than
the minimal OS sleep time
- Only wake asynchronous timer thread to queue new timer events
that are shorter than the currently shortest scheduled event
Also:
- Avoid potential divide by zero when stopping a running calibrated clock.
- Quickly reflect newly calibrated clock info in additional timers that may be running
Also:
- allow a timer to dynamically stop itself (by calling sim_rtcn_calb
with tps=0), and then to start the internal timer to provide a calibration
baseline if necessary.
- Fix coschedule interval computation when the queue is empty.
- Properly select the correct timer for coscheduling without a specific tmr
- Properly adjust the coschedule queue's next time value when entries are
canceled.
- Cleaned up throttling to behave well with all potential throttling rates and
to make visible what is happening when boundaries are reached.
Additionally, calls to sim_activate_after with delay values that exceed
twice the tick size of the calibrated clock are now coscheduled with
the calibrated clock.
Historically, hosts which have a tick size slower than the tick a simulator
wants to implement can't idle effectively and keep good time.
This change allows simulators which call sim_rtcn_tick_ack() to provide
useful idling behavior while still keeping the passage of wall clock time
to time in the simulator accurate.
Also:
- Added more statistics
- Made sleep measurements more precise
- Correct idle sleep decision logic without regard to host tick size
- Fix calibration setup/teardown when host tick size is large (>10ms)
- Generalized large host tick test capability (MS_MIN_GRANULARITY)
- Fixed Windows sim_os_msec() to always use timeGetTime()
- Fixed coschedule routines (that don't mentoin a tmr) to default to
timer 0 and fallback to the internal timer otherwise.
- Removed dependency on sizeof(tv_sec) in timespec structure for MinGW
Clock devices which call sim_register_clock_unit or sim_register_clock_unit_tmr
are best behaved if they use sim_activate_after to schedule their tick events.
When the timer subsystem hasn't gotten fully initialized, devices may
attempt to coschedule schedule events before the clock has gotten
far enough along to be fully initialized. When this happens we now
make sure to avoid the potential for a zero delay which will may cause
an infinite scheduling loop.
Asynchronous clocks are now built for all simulators which are built with
SIM_ASYNCH_IO defined. The default behavior has asynchronous clocks
disabled since this is still experimental, but it can be enabled with
SET TIMER ASYNC.
Catchup clock ticks are now available, but since they're experimental,
they aren't enabled by default. Catchup ticks are only available if the
simulators clock device calls sim_rtcn_tick_ack to acknowledge processing
of clock ticks. The VAX simulators have been modified to leverage this.
Catchup clock ticks can be enabled with SET TIMER CATCHUP
Additionally, an idle threshold is provided which can be used to
influence when clock calibration may be suppressed. The default is not
to suppress calibration activities.
The various timer behaviors are visible with the SHOW TIMER command.
The state of the operating timer facilities is visible with: SHOW CLOCK
Timer events which are queued are visible with the SHOW QUEUE command.
- Timers that schedule their ticks with sim_activate_after() now operate
consistently without having to be the single timer used by a simulator.
- Simulators which dynamically enable the operation of a clock when one
wasn't previously wasn't enabled will disable the internal calibrated timer.
- Generate reasonable messages when presented with erroneous throttle input.
- Add throttling recalibration logic if only if target rate drift exceeds 5%
Reworked all priority adjustment code to leverage a new
sim_os_set_thread_priority API which is coded to use pthreads or OS
priority adjustment APIs as necessary.
These changes facilitate more robust parameter type checking and helps
to identify unexpected coding errors.
Most simulators can now also be compiled with a C++ compiler without
warnings.
Additionally, these changes have also been configured to facilitate easier
backporting of simulator and device simulation modules to run under the
simh v3.9+ SCP framework.
SET CPU IDLE={OS{:n}} where n is the idle stability delay
which is also the clock calibration delay.
A -D switch on a SHOW -D CPU IDLE command will
display the stability delay as will a SHOW CLOCK command.
