I'm just done with refactoring, as was planned in
http://lists.squeakfoundation.org/pipermail/vm-dev/2008-February/001795.html.
I was surprised that VM runs smoothly at first successful build after
changing lot of stuff! :)

Here the set of changes i done:
---------
* refactor signaling low space semaphore
* refactor signaling interrupt semaphore
* refactor signaling finalization semaphore
* remove interruptPending var
* remove get/setInterruptPending methods

* set system timer to post ioProcessEvents event every 200 ms

* deal with primitiveSignalAtMilliseconds primitive
* refactor signaling timer semaphore
* remove lastTick var
* remove nextPollTick var
* remove nextWakeupTick var
* remove get/setNextWakeupTick methods

* change internalQuickCheckForInterrupts
* remove quickCheckForInterrupts, leave only internalQuickCheckForInterrupts

* remove checkForInterrupts method
* interruptChecksEveryNms totally ignored (no need in interrupt if
there no any event!)
* remove interruptCheckForced method from use
* remove getInterruptCheckCounter method
* remove setInterruptCheckCounter: method
* remove interruptCheckCounter var
* forceInterruptCheck method is no-op now
* remove interruptCheckCounterFeedBackReset var

---------

1 tinyBenchmarks runs on my box:

squeak VM:
'200312989 bytecodes/sec; 5879195 sends/sec'
'200469851 bytecodes/sec; 6178049 sends/sec'
'200000000 bytecodes/sec; 6183469 sends/sec'
'200156372 bytecodes/sec; 6151095 sends/sec'

HydraVM before refactoring of checkForInterrupts()

'194973343 bytecodes/sec; 5372831 sends/sec'
'195121951 bytecodes/sec; 5372831 sends/sec'
'195121951 bytecodes/sec; 5368739 sends/sec'
'194973343 bytecodes/sec; 5126658 sends/sec'

HydraVM after refactoring of checkForInterrupts()
'197378565 bytecodes/sec; 5183202 sends/sec'
'195121951 bytecodes/sec; 5126658 sends/sec'
'197378565 bytecodes/sec; 5308098 sends/sec'
'197530864 bytecodes/sec; 5368739 sends/sec'

It's strange that
[ 3000 milliSeconds asDelay wait ] timeToRun
prints 2500 ( 4000 milliSeconds will print 3500, seems somewhere there
is a constant subtraction placed ?)

Is there are some tests for how precise Delays working?

Okay, now need to do some testing, and then i will release the update.

-- 
Best regards,
Igor Stasenko AKA sig.