John,

I've been running into this problem at various times - turns out that
#standardTime: on any recent Windows machine will give you anything
_but_ standard conditions (due to swapping etc). The best thing you can
do is just ignore it ;-) With respect to #copySmartsRoot: you will
notice that there's an upper limit set for the initial size, so that
actually works quite well.

Cheers,
  - Andreas

> -----Original Message-----
> From: squeak-dev-admin at lists.squeakfoundation.org 
> [mailto:squeak-dev-admin at lists.squeakfoundation.org] On 
> Behalf Of John M McIntosh
> Sent: Tuesday, February 19, 2002 2:41 AM
> To: squeak-dev at lists.squeakfoundation.org
> Subject: A problem with standardTime:
> 
> 
> standardTime: aBlock
> 	"Times the execution of aBlock in milliseconds, under the 
> following standard conditions:  exactly 10Mb of free space is 
> available and compacted, and the recent VM statistics are reset 
> immediately before execution."
> 	| spaceLeft tieDown |
> 	spaceLeft _ Smalltalk garbageCollect.
> 	spaceLeft < 1e7 ifTrue: [self error: 'not enough space for 
> standard conditions'].
> 	tieDown _ ByteArray new: spaceLeft - 1e7.  "Leave 
> exactly 10MB free"
> 
> 
> Now the problem comes in when the VM can autosize, but the autosizing 
> doesn't take Virtual Memory considerations into account. The 
> Smalltalk garbageCollect
> returns the maximum size we can grow to, versus say a size that won't 
> cause page swapping.
> 
> So on my mac this returns
> 
> 517759868
> 
> As you can see we then run off and allocate 517759868 - 10000000.
> 
> But on a machine that only *has* 512MB of memory, lots of things are 
> paged out and a historically significant event called *page 
> thrashing* occurs.
> 
> Now I think Dan wrote this, and perhaps it needs to be rethinked.
> 
> I'm not sure on unix machines you can really ask what the 'safe' 
> limit it, after all the objective of VM operating systems is to allow 
> you to run applications that don't fit into real memory boundaries.
> 
> So I'll welcome a change set
> 
> Also the max size is used in
> ImageSegment>>copySmartRootsExport: rootArray
> for some decision on characteristics of an algorithm to be run.
> 
> -- 
> --
> ==============================================================
> =============
> John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
> Corporate Smalltalk Consulting Ltd.  
> http://www.smalltalkconsulting.com
> 
> ==============================================================
> =============
> 
>