Dear Morten,

Sorry for the delayed response.  I have submitted your inquiry to the the 
appropriate people at IBM and received the following reply:

--------------

The libspe (version 1.2) was based upon a prototype runtime that was 
created by the small SW team for the expressed purposes of Cell processor 
bringup. With this implementation, we all realized that it had some very 
fundamental limitations that we want to address as we bring full 
production libraries forward.  This is the reason libspe (version 2, also 
known as libspe2), exists. The intent is that libspe1.2 will be deprecated 
and that all future development should use libspe2.  The version of 
libspe2 released in SDK 2.0 was early prototype code and did not go 
through our formal testing procedures. The next release of the SDK is 
planned to fully and exclusively use libspe2. This means that all code 
samples will be ported to libspe2. A migration guide is also planned with 
this release to assist developers in the migration of libspe 1.x code to 
libspe2.  The libspe 1.x libraries should continue to be available, but 
their use is not encouraged. 

Your example of 30 contexts, 30 program loads, and 30 runs will work 
depending upon the scheduling attributes of the threads. SDK 2.0 only 
supports a run-to-completion scheduling policy.  Therefore, the run 
request will block until a SPE is available. Future SDKs are expected to 
support standard linux scheduling polices like round robin (SCHED_RR) so 
that SPE threads are pre-empted. 

Note: Don't forget, in your example, you must also create 30 thread 
(pthreads) of execution. Otherwise, the first spe_context_run will block 
until the SPE completes. 

I hope this helps. 

Sincerely,

Dan B.
-------------------------------------------------------------------------------
Daniel A. Brokenshire
STSM / Emerging Products Development
brokensh@us.ibm.com               512-838-3373

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==========================
Gary Beckwith
IBM Customer Connect
beckwith@us.ibm.com
(802) 769-6312, t/l 446-6312
home office (802) 434-4939


 
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I have a comment regarding libspe. You dont make it clear anywhere in the 
documentation for libspe2.0 why you found it necessary to provide two 
concurrently existing APIs for spe development (libspe1.2 being the 
other). Id very much like for you to clearify this.
Also I dont feel its clear what happens if more calls are made to 
spe_program_load() then the system has SPUs. For instance when using 
ps3linux there are physically 6 available to the developer. What happens 
if first spe_program_load was called 30 times for 30 diff contexts then 
next spe_contex_run() is called 30 times. Would this work? Would it 
postspone the actual load into local storage when the run is performed? If 
so do loads get cached if the program is already available on an spu? If 
not and it actually does get loaded into local storage in the load call 
then what happens after 6 loads? Will it block all subsequent loads until 
a run is called? Or will it simply return error codes? I felt these things 
were not clear from the documentation.