Re: Does Ada tasking profit from multi-core cpus?

["Steve" <nospam_steved94@comcast.net>]

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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:rgcukvs1j6ck$.1vjj69zzy1h56$.dlg@40tude.net...
> On 5 Mar 2007 02:08:22 -0800, Ludovic Brenta wrote:
>
>> "�  jpluto" wrote:
>>> Has someone experience with Ada tasking (especially GNAT) on multi-core
>>> systems?
>>>
>>> Show programs with several working tasks a performance boost on 
>>> dual-core or
>>> quad-core cpus?
>>
>> On my dual-core Turion 64 with Debian GNU/Linux and GCC 4.1.2, all is
>> well. Ada programs using tasking use both cores. I think it would work
>> on most other platforms too, but YMMV.
>
> Apart from using both cores, does anybody know how protected objects
> function on multi-cores? Especially:
>
> 1. Whether protected object's functions are indeed executed concurrently
> when come from the tasks running on different cores?
>
> 2. What are the times required to take/release the protected object's spin
> lock compared to ones on single core?
>
> 3. Can a task switch cores? If yes, what is the overhead of switching?

On Windows, which uses symmetric multiprocessing, I belive two cores works 
the same as two CPU's.  With two CPU's the two highest priority threads that 
are in the ready state run concurrently, so yes a task can switch cores. 
Sorry I don't know about the overhead of switching.
I have run tests on a system with 2 CPU's and found that a single task that 
does a lot of switching winds up using 50% of the CPU time on both CPU's 
(from the task viewer).

Regards,
Steve
(The Duck)

>
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de