[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
> ===========================================================================
>
>
>
>
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