[Vm-dev] OS X Mavericks & cog tickers

[Eliot Miranda]

On Thu, Oct 24, 2013 at 4:25 PM, John McIntosh <
johnmci at smalltalkconsulting.com> wrote:

>
> Must not hit enter...
>
> relinquishProcessorForMicroseconds
> may or may not one has to find the actual code and maybe it is platform
> dependent etc etc.
>
> An attempt was made to ask the VM what the next wakeup time is. The VM
> actually knows this it's the bottom end of the Delay logic.
> We then sleep to this tick, using a call that should awake the process if
> an BSD interrupt (ill defined) arrives.
>
> In here we also service socket handles etc and oh maybe some other house
> keeping.
>
> Still the objective was to sleep until we have to wake up for Morphics 50
> times a second poll, or some UI/socket/interrupt arrives.
>

But the objective should be to sleep until theres' something to do:
- i/o is possible
- a delay has expired
- a callback from some other thread has occurred (if the VM is
multi-threaded)
Otherwise it should block forever.

This "pause for a little while" is bogus.


>
> In practice there are some artifacts like the Scheduler saying go to sleep
> but awake -2 milliseconds ago because of some race condition with in the
> Delay logic. (good luck finding that)...
>
>
>
>
> On Thu, Oct 24, 2013 at 7:18 PM, John McIntosh <
> johnmci at smalltalkconsulting.com> wrote:
>
>> Well let me reflect.
>> Nothing has changed, the VM energy sapping field is the same as
>>  yesterday, just more evident.
>>
>>  I wasn't able to determine what code base is used, but if I go back 5 or
>> 10 years.
>>
>> (a) The morphic event polling cycle runs 50 times a second. One could
>> write some timer consolidation code there to consider when do I have to
>> wake up and paint all those morphs? No C/Objective-C/assembler/fortran
>> required...
>>
>> (b) Maybe the VMs are event driven now and Morphic does not need to poll
>> 50 times a second?
>>
>> (c) The BSD Unix socket system requires polling of some form.  But see
>> work by Craig 10-15 back on "Flow"
>>
>> (d) When all the Smalltalk Processes settle, the dispatcher runs the
>> lowest priority task which calls relinquishProcessorForMicroseconds with
>> a bogus value.
>>
>>
>>
>>
>> On Thu, Oct 24, 2013 at 6:21 PM, tim Rowledge <tim at rowledge.org> wrote:
>>
>>>
>>> Looking through some of the low-level changes in Mavericks I noticed
>>> stuff about timer consolidation. I *think* that it is something that you
>>> can offer to allow, rather than something done unto you code, but almost
>>> certainly it will have some sort of impact on the heartbeat ticker type of
>>> code used in stackvm/cog. Where is a skilled Mac vm maintainer when you
>>> need one?
>>>
>>> tim
>>> --
>>> tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
>>> "bOtHeR" said Pooh, mistaking the LSD tablet for aspirin
>>>
>>>
>>>
>>
>>
>> --
>>
>> ===========================================================================
>> John M. McIntosh <johnmci at smalltalkconsulting.com>
>> Corporate Smalltalk Consulting Ltd. Twitter: squeaker68882
>>
>> ===========================================================================
>>
>>
>
>
> --
> ===========================================================================
> John M. McIntosh <johnmci at smalltalkconsulting.com>
> Corporate Smalltalk Consulting Ltd. Twitter: squeaker68882
> ===========================================================================
>
>
>


-- 
best,
Eliot
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