8 core Mac Pro: Squeak and Croquet

>From: Daniel Lanovaz <[hidden email]>
>Reply-To: The general-purpose Squeak developers
>list<[hidden email]>
>To: [hidden email]
>Subject: 8 core Mac Pro: Squeak and Croquet
>Date: Sat, 21 Apr 2007 11:06:14 -0700
>
>The following are some screenshots of the CPU monitor
>(one bar per core) running Squeak and Croquet on the
>latest 8 core Mac Pro.
>
>It appears true that Tiger does elicit "core swapping"
>behavior, the movement of threads between cores as they
>execute. The performance monitor showed Squeak having two
>threads, with activity on all 8 cores during normal operation
>(except during one of the infinite loop tests), where the
>core activity includes, of course, OS threads for window
>management, etc.
>
>This test was certainly not scientific.
>
>With Squeak/Croquet riding atop 24 GHz of
>64-bit compute power, plus the muscle of an ATI X1900
>GPU, the text editing appears to go smoothly. ;-)
>
>The core swapping issue may supposedly be altered in Leopard.
>There is probably little performance degradation if the
>thread stays on one quad-core chip with the shared L2 cache,
>but if the thread moves to another quad-core chip, the
>(instruction/data) cache contents need to be reloaded on the
>second chip. The second Squeak infinite loop test appears
>to show the main Squeak thread moving between two
>quad-core chips.
>
>I purchased this machine for 3D animation rendering. My
>render software wonderfully takes advantage of all 8
>cores, with some impressive performance gains.
>
>Cheers,
>Daniel
>
>CPU core usage
>==============
>
>Squeak GUI activity:
> http://idisk.mac.com/iphone2007-Public/Squeak/squeak-8-core-01.jpg
>
> NOTE: Lots of dragging in a text view.
>
>Squeak in an infinite loop:
> http://idisk.mac.com/iphone2007-Public/Squeak/squeak-8-core- 
>infinite-02.jpg
>
> NOTE: Squeak is remaining on 1 core as nothing
> else happens on the system.
>
>Squeak in an infinite loop (switching applications):
> http://idisk.mac.com/iphone2007-Public/Squeak/squeak-8-core- 
>infinite-03.jpg
>
> NOTE: Squeak's infinite loop is moving between cores
> as I switch between applications.
>
>Croquet GUI activity:
> http://idisk.mac.com/iphone2007-Public/Squeak/croquet.1.0.18-8-core.jpg
>
> NOTE: I was just walking around inside a space.
>

>
>> From: Daniel Lanovaz <[hidden email]>
>> Reply-To: The general-purpose Squeak developers list<squeak-
>> [hidden email]>
>> To: [hidden email]
>> Subject: 8 core Mac Pro: Squeak and Croquet
>> Date: Sat, 21 Apr 2007 11:06:14 -0700
>>
>> The following are some screenshots of the CPU monitor
>> (one bar per core) running Squeak and Croquet on the
>> latest 8 core Mac Pro.
>>
>> It appears true that Tiger does elicit "core swapping"
>> behavior, the movement of threads between cores as they
>> execute. The performance monitor showed Squeak having two
>> threads, with activity on all 8 cores during normal operation
>> (except during one of the infinite loop tests), where the
>> core activity includes, of course, OS threads for window
>> management, etc.
>>
>> This test was certainly not scientific.
>>
>> With Squeak/Croquet riding atop 24 GHz of
>> 64-bit compute power, plus the muscle of an ATI X1900
>> GPU, the text editing appears to go smoothly. ;-)
>>
>> The core swapping issue may supposedly be altered in Leopard.
>> There is probably little performance degradation if the
>> thread stays on one quad-core chip with the shared L2 cache,
>> but if the thread moves to another quad-core chip, the
>> (instruction/data) cache contents need to be reloaded on the
>> second chip. The second Squeak infinite loop test appears
>> to show the main Squeak thread moving between two
>> quad-core chips.
>>
>> I purchased this machine for 3D animation rendering. My
>> render software wonderfully takes advantage of all 8
>> cores, with some impressive performance gains.
>>
>> Cheers,
>> Daniel
>>
>> CPU core usage
>> ==============
>>
>> Squeak GUI activity:
>> http://idisk.mac.com/iphone2007-Public/Squeak/squeak-8-core-01.jpg
>>
>> NOTE: Lots of dragging in a text view.
>>
>> Squeak in an infinite loop:
>> http://idisk.mac.com/iphone2007-Public/Squeak/squeak-8-core- 
>> infinite-02.jpg
>>
>> NOTE: Squeak is remaining on 1 core as nothing
>> else happens on the system.
>>
>> Squeak in an infinite loop (switching applications):
>> http://idisk.mac.com/iphone2007-Public/Squeak/squeak-8-core- 
>> infinite-03.jpg
>>
>> NOTE: Squeak's infinite loop is moving between cores
>> as I switch between applications.
>>
>> Croquet GUI activity:
>> http://idisk.mac.com/iphone2007-Public/Squeak/croquet.1.0.18-8- 
>> core.jpg
>>
>> NOTE: I was just walking around inside a space.
>>
>
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>I'll note it was discussed on the VisualWorks mailing list that there  is a
>large performance hit if you allow a process to switch from
>one CPU core to another, which Daniel notes below. Windows provides  an API
>call that allows you to mark an application to be dedicated
>to a CPU core, but that led to more discussion about how this was not  a
>good solution either. Really the Operating System Vendors need to
>be a bit better in their process switching algorithms and ensure a  
>restarted thread should restart on the same CPU core to  take  advantage of
>any existing cached bits.  This issue should not rely on special need  
>cases hacked by any old programmer.