[squeak-dev] What is meant by 'shrink' in the VM parameters?

Ken Causey ken at kencausey.com
Fri Oct 22 20:08:35 UTC 2010


On Fri, 2010-10-22 at 11:43 -0700, John M McIntosh wrote:
> Further to this you should consider the setting for setGCBiasToGrow
> and what are the numbers out of 
> 
> 	3	end of memory (read-only)
> 	31	number of grow memory requests (read-only)
> 	32 number of shrink memory requests (read-only) 

We haven't been charting them but we have been watching the values of 3
and 32 as well as 2, 7, and 9.  32 moves in lockstep with 7 (full GCs
since startup.  I'll add 31 to the figures we watch.

> I'll suggest you chart them by time to understand what the spikes are? 
> does it go from 60MB to 180MB then back to 60MB in a second? and pound #31 up by 20? 

What does the speed at which the usage climbs or drops matter?  I can't
answer about 31 yet but I'll let you know.

Ken

> 
> On 2010-10-22, at 6:24 AM, Ken Causey wrote:
> 
> > I'm wondering what 'shrink' means in the following VM parameter
> > comments:
> > 
> > "24 memory threshold above which shrinking object memory (rw)"
> > 
> > and
> > 
> > "32 number of shrink memory requests (read-only)"
> > 
> > My first thought is that a shrink represents Squeak release memory back
> > to the operating system once it is no longer needed.
> > 
> > As I've mentioned before we are trying to reduce the RAM footprint of
> > the www.squeak.org process and are watching various related figures.
> > 
> > We can see the value in VM parameter 32 increase, but while the value
> > for parameter 3 (end of memory) goes down as you would expect, the
> > operating system's view of the memory usage does not change.
> > 
> > Ken
> > 
> 
> --
> ===========================================================================
> John M. McIntosh <johnmci at smalltalkconsulting.com>   Twitter:  squeaker68882
> Corporate Smalltalk Consulting Ltd.  http://www.smalltalkconsulting.com
> ===========================================================================
> 
> 
> 
> 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 190 bytes
Desc: This is a digitally signed message part
Url : http://lists.squeakfoundation.org/pipermail/squeak-dev/attachments/20101022/9c39b18e/attachment.pgp


More information about the Squeak-dev mailing list