Now I have more than the tail of the snake:

Stephan Rudlof wrote:
> Dear All,
> 
> I have the tail of the snake:
> 
> Stephan Rudlof wrote:
> 
>>PS: My Squeak3.8alpha#6285 stems from upgrading a Squeak3.6 image: could
>>this be the reason for the hassle? Is there a difference between an
>>actual image and upgrading a 3.6 one?
> 
> 
> There is! With the one from
> ftp://st.cs.uiuc.edu/pub/Smalltalk/Squeak/3.8alpha/Squeak3.8a-6285-unstable.zip
> I have times like Stef (same magnitude, I have a slower processor)!
> 

> Why is there this difference?

The difference is, that the fresh image has fewer classes!
For me it is
  Smalltalk allClasses size
-> 2136 for the incrementally generated 3.8, and
-> 1683 for the fresh one.

Making some tests with sets of symbols:
---------------------------------------
| symbols symbolsSet block |
numOfSymbols _ 1500.
symbols := (1 to: numOfSymbols) collect: [:num | num asString asSymbol].
block _ [symbolsSet _ symbols asIdentitySet.
		[symbols do: [:sym | symbolsSet remove: sym]] timeToRun].
{block value. block value. block value}.

 #(11660 11558 11832) #(11627 11553 11744) #(11629 11568 11521)
"numOfSymbols _ 2500."

 #(311 310 317) #(318 327 314) #(309 331 312) "numOfSymbols _ 2000."

 #(63 67 59) #(81 74 70) #(52 56 54) "numOfSymbols _ 1500."
--------------------------------------

gives a big change in performance just between these values!

The conclusions are changing:

> 
> Conclusions:

> - The BehaviorHashEnh cs is *not* needed for an *actual* image *not*
> being reached by incremental upgrading.

This is not true: the BehaviorHashEnh cs makes sense, if there are some
more classes in the image (e.g. by loading some packages from SM).

> - This result could be relevant for people just incrementally upgrading
> their images!

Without this changeset: indeed!


Like I've written in the cs comment:
===
Future: Best would probably be a better identityHash with more bits
(possibly in V4?).
===

Suggestion: it could make sense to mark the changed methods for to be
reworked after having more identityHash bits.


Greetings
Stephan

> 
> 
> Greetings
> Stephan
> 
> 
>>Stephan Rudlof wrote:
>>
>>
>>>Stef,
>>>
>>>I'm trying to think freshly, since this is very weird: I have measured
>>>with a fresh 3.8alpha...
>>>
>>>My results for the IdentitySet variant have been *much* worser than
>>>yours, with or without the cs (which is expected, since the behavior of
>>>IdentitySet won't be affected by the cs).
>>>For this reason, the idea of the cs has been to introduce Behavior>>hash
>>>- using String>>hash - to avoid the default Object>>hash which itself
>>>calls ProtoObject>>identityHash. This is also the reason, why the
>>>IdentitySet variant remains worse for my system (it just continues to
>>>use >>identityHash).
>>>But the cs doesn't seem to have a relevant effect in your system,
>>>because *your* >>identityHash seems to work much better than mine!
>>>
>>>Now the question: why?
>>>
>>>ProtoObject>>identityHash calls a prim: which VM are you using?
>>>
>>>It would be nice, if some other person would doIt the following
>>>expression and post the result together with the VM version (squeak
>>>-version) and processor version to get some more data.
>>>
>>>
>>>DoIt
>>>----
>>>
>>>| allClasses allClassesSet block |
>>>	allClasses := Smalltalk allClasses.
>>>	block _ [allClassesSet _ allClasses asIdentitySet.
>>>			[allClasses do: [:class | allClassesSet remove: class]] timeToRun].
>>>	{block value. block value. block value}.
>>>
>>>
>>>For me the result is
>>>
>>> #(3112 3166 3108)
>>>
>>>for
>>>
>>>sr at karl:~/DepS/Tmp$ squeak -version
>>>3.7b-5 #1 Mon Jun 14 18:05:35 CEST 2004 gcc 3.3.3
>>>Squeak3.7beta of '1 April 2004' [latest update: #5954]
>>>Linux karl 2.4.26sr #1 Sun May 23 19:28:24 CEST 2004 i686 GNU/Linux
>>>default plugin location: /usr/local/lib/squeak/3.7b-5/*.so
>>>
>>>at a 366MHz Pentium.
>>>
>>>Any additional ideas for the huge difference between mine and Stefs
>>>results are also welcome.
>>>
>>>
>>>Greetings
>>>Stephan
>>>
>>>stéphane ducasse wrote:
>>>
>>>
>>>
>>>>| allClasses allClassesSet block |
>>>>	allClasses := Smalltalk allClasses.
>>>>	block _ [allClassesSet _ allClasses asSet.
>>>>			[allClasses do: [:class | allClassesSet remove: class]] timeToRun].
>>>>	{block value. block value. block value}
>>>>
>>>>one before
>>>>	#(27 27 25)
>>>>one after
>>>>	#(31 35 32)
>>>>
>>>>| allClasses allClassesSet block |
>>>>	allClasses := Smalltalk allClasses.
>>>>	block _ [allClassesSet _ allClasses asIdentitySet.
>>>>			[allClasses do: [:class | allClassesSet remove: class]] timeToRun].
>>>>	{block value. block value. block value}.
>>>>
>>>>two before
>>>>	#(19 19 19)
>>>>two after
>>>>	 #(37 19 22)
>>>>
>>>>
>>>>I hope this helps. This was with 6273
>>>>
>>>>Stef
>>>>
>>>>
>>>
>>>
> 

-- 
Stephan Rudlof (sr at evolgo.de)
   "Genius doesn't work on an assembly line basis.
    You can't simply say, 'Today I will be brilliant.'"
    -- Kirk, "The Ultimate Computer", stardate 4731.3