[squeak-dev] setting VM Parameter?

Yoshiki Ohshima yoshiki at vpri.org
Wed Jan 4 05:39:18 UTC 2012

At Tue, 3 Jan 2012 17:35:09 -0800,
Eliot Miranda wrote:
> Hi Yoshiki,
> On Tue, Jan 3, 2012 at 4:29 PM, Yoshiki Ohshima <yoshiki at vpri.org> wrote:
>      Hello,
>      On the latest Cog VM and my image (not so latest), I don't seem to
>     be able to get and set some vm parameters.  Specifically, the ones
>     marked as "read-write" in the method comment give me "nil" when
>     queried, and some strange value when try to set.  Is this a known
>     issue?  And/or, Is there an image side change I should have?
> Which indices exactly?  The comment might be wrong.  The Cog and Stack VMs have a modified garbage collector in which certain parameters no longer make sense and are answered as nil.  I need
> to know which indices to distinguish between intended behaviour and a bug (and the comment might merely be wrong).  Also which VM exactly?  i.e. what do you get for (1006 to: 1009) collect:
> [:i| Smalltalk getSystemAttribute: i]?

Thank you, Eliot.

The result from above do it is:

 #('Mac OS X built on Dec 13 2011 16:01:43 Compiler: 4.2.1 (Apple Inc. build 5666) (dot 3)' 'CoInterpreter VMMaker.oscog-eem.140 uuid: 2487009c-2c13-4609-b89e-77f0e195f433 Dec 13 2011' 'StackToRegisterMappingCogit VMMaker.oscog-eem.139 uuid: c2849383-9768-4948-b9b2-a5c22d482b07 Dec 13 2011' 'r2522 http://www.squeakvm.org/svn/squeak/branches/Cog')

But also happen with: 
 #('Mac OS X built on Apr 26 2011 18:24:51 Compiler: 4.2.1 (Apple Inc. build 5666) (dot 3)' 'CoInterpreter VMMaker.oscog-eem.56 uuid: fbf17bd2-ddbc-488f-b70d-3b9ba8906430 Apr 26 2011' 'StackToRegisterMappingCogit VMMaker-oscog.51 uuid: d213bf61-5898-475b-8a5c-e4a9bdad2415 Apr 26 2011' nil)

And I was wrong about "the ones marked as 'read-write'".  The result
from (1 to: 40) select: [:i| (Smalltalk vmParameterAt: i) isNil] is
#(4 5 34).

The one I was originally interested in is 5, which the comment says
"allocations between GCs (read-write)".  In my animation framework I
see hiccups and trying to mitigate it.

But now I increased the parameter 6 ("survivor count tenuring
threshold (read-write)"), I see no hiccups.  Ok, so vm parameter 5 not
working is not critical, but I'd still want to fiddle the number to
experiment (if it is still relevant).

-- Yoshiki

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