(no subject)

> Hello, all-
>
> I've written a relatively long-running search program (started it
> yesterday afternoon, and it was still chugging away when I left the
> house this morning).  I can leave it going indefinitely on my desktop
> PC, but I noticed in the task manager that the Squeak process was using
> exactly 50% of available CPU.  This remains the same regardless of
> whether the VM preference for "reduce CPU usage" is checked.  In the
> image itself, the "higherPerformance" preference is checked.
>
> (This is under Squeak 3.9 on a WinXP machine.  If I remember correctly,
> the CPU itself is one of the vintage 2005 hyperthreading Intel chips.)
>
> Is there a way to tell the VM to hog the CPU?  Failing that, would there
> be any significant reason *not* to start a second Squeak session to run
> another such job at the same time?  (=
>
> Thanks,
> -Sam Livingston-Gray
>  comp.sci. senior, Portland State University
>
>
>

> Hello, all-
>
> I've written a relatively long-running search program (started it
> yesterday afternoon, and it was still chugging away when I left the
> house this morning).  I can leave it going indefinitely on my desktop
> PC, but I noticed in the task manager that the Squeak process was
> using exactly 50% of available CPU.  This remains the same regardless
> of whether the VM preference for "reduce CPU usage" is checked.  In
> the image itself, the "higherPerformance" preference is checked.
>
> (This is under Squeak 3.9 on a WinXP machine.  If I remember
> correctly, the CPU itself is one of the vintage 2005 hyperthreading
> Intel chips.)
>
> Is there a way to tell the VM to hog the CPU?  Failing that, would
> there be any significant reason *not* to start a second Squeak
> session to run another such job at the same time?  (=
>
> Thanks,
> -Sam Livingston-Gray
>   comp.sci. senior, Portland State University
>
>
>

> Check if you have a CPU with Hyperthreading. On Windows, that  
> behaves like a dual-core machine, so 50% CPU is simply the max you  
> get for any single thread.
>
> Cheers,
>   - Andreas
>
> Sam Livingston-Gray wrote:
>> Hello, all-
>> I've written a relatively long-running search program (started it  
>> yesterday afternoon, and it was still chugging away when I left  
>> the house this morning).  I can leave it going indefinitely on my  
>> desktop PC, but I noticed in the task manager that the Squeak  
>> process was using exactly 50% of available CPU.  This remains the  
>> same regardless of whether the VM preference for "reduce CPU  
>> usage" is checked.  In the image itself, the "higherPerformance"  
>> preference is checked.
>> (This is under Squeak 3.9 on a WinXP machine.  If I remember  
>> correctly, the CPU itself is one of the vintage 2005  
>> hyperthreading Intel chips.)
>> Is there a way to tell the VM to hog the CPU?  Failing that, would  
>> there be any significant reason *not* to start a second Squeak  
>> session to run another such job at the same time?  (=
>> Thanks,
>> -Sam Livingston-Gray
>>  comp.sci. senior, Portland State University
>
>

> On Fri, 4 May 2007 20:35:21 +0200, "Damien Pollet"
> <[hidden email]> wrote:
>
>> Windows would probably report 100% CPU usage, but I doubt the CPU
>> would go twice as fast... HT means a single core can run instructions
>> from two threads simultaneously, not that the transistors are
>> partitioned into two half-cores. Surely all computing units are  
>> shared
>> among threads?
>
> No, with hyperthreading, the BIOS basically builds two virtual  
> processors,
> and each one gets half of the CPU speed.

> On Fri, 4 May 2007 15:58:40 -0400, Bert Freudenberg  
> <[hidden email]>
> wrote:
>
>> I'm pretty sure this is not true, but more like what Damien wrote.
>> Basically all that HT does is having a second register set so you can
>> hold the state of two processes in the CPU at the same time.
>> Execution units are shared. Since one process seldomly utilizes all
>> execution units (due to "pipeline bubbles") the other process can use
>> the free units. This simply enhances throughput, but it's not like in
>> one process you only ever get half the speed.
>
> Okay, well perhaps I misunderstood. I know a couple years ago we did a
> bunch of research into this, because we were running 4-processor  
> servers
> with hyperthreading in each processor, and we were running 4 VisualAge
> server images on each machine. By turning off Hyperthreading, we  
> got a very
> significant speed increase (not quite double, but close). With
> hyperthreading on, we only ended up ever using 50% of the total CPU
> available.

>On May 4, 2007, at 16:20 , Jon Hylands wrote:
>
>>On Fri, 4 May 2007 15:58:40 -0400, Bert Freudenberg
>><[hidden email]>
>>wrote:
>>
>>>I'm pretty sure this is not true, but more like what Damien wrote.
>>>Basically all that HT does is having a second register set so you can
>>>hold the state of two processes in the CPU at the same time.
>>>Execution units are shared. Since one process seldomly utilizes all
>>>execution units (due to "pipeline bubbles") the other process can use
>>>the free units. This simply enhances throughput, but it's not like in
>>>one process you only ever get half the speed.
>>
>>Okay, well perhaps I misunderstood. I know a couple years ago we did a
>>bunch of research into this, because we were running 4-processor
>>servers
>>with hyperthreading in each processor, and we were running 4 VisualAge
>>server images on each machine. By turning off Hyperthreading, we
>>got a very
>>significant speed increase (not quite double, but close). With
>>hyperthreading on, we only ended up ever using 50% of the total CPU
>>available.
>
>Well, then I'd take your experience over Intel's marketing I guess ;)
>
>The idea actually is rather old, IIRC the Alto was 16-ways
>"hyperthreaded".
>
>- Bert -
>
>