On May 18, 2007, at 8:25 AM, Andreas Raab wrote:

> Hi John -
>
> John M McIntosh wrote:
>> It also btw had code in SophieMemoryPolicy >>calculateGoals that  
>> adjusted Smalltalk vmParameterAt: 5 and 6 to target a 1 ms  
>> incremental GC time. A singleton instance wakes up every 5 seconds  
>> and peeks at the GC statistical data. However I've not been doing  
>> this adjustment.
>
> I'm actually more shooting for 5ms IGC times but having a process  
> which tweaks these parameters is an interesting idea too.


Ok, I had thought you usually were thinking of 1ms igc times because  
that means 1ms accuracy Delay pops. If you target a 5ms won't you  
risk Delays being off by 5ms?


Also the VM uses these grow/shrink values by default.

	growHeadroom := 4*1024*1024. "four megabyte of headroom when growing"
	shrinkThreshold := 8*1024*1024. "eight megabyte of free space before  
shrinking"

I don't think anyone overrides the values, say like

	Smalltalk vmParameterAt: 25 put: 24*1024*1024. "grow headroom"
	Smalltalk vmParameterAt: 24 put: 48*1024*1024.  "shrink threshold"


In the Memory policy task you might look at how much grow/shrinking  
is going on to avoid excessive grow/shrink actions based on your  
choices for bias to grow.


--
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John M. McIntosh <johnmci at smalltalkconsulting.com>
Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
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