[Cbe-oss-dev] The use of __spe_context_update_event() is inefficient for the debugger

[Ulrich Weigand]

Hi John,

> The debugger would look for "__spe_context_update_event_id", and if 
> it is defined set a breakpoint there, and when the breakpoint is hit
> by the target process, it can look at R3 to get the id. Otherwise 
> for compatibility, if "__spe_context_update_event_id" is *not* 
> defined and "__spe_context_update_event" is defined, the when the 
> breakpoint is hit, it cannot rely on the contents of R3 and must 
> inspect all of the SPU contexts.

Yes, exactly.

> I see, that makes sense for GDB, but TotalView handles SPU thread 
> address spaces differently. In the TotalView debugger, each SPU 
> thread is modeled as a "thread with a discrete address space" 
> separate from the PPU process's address space, so when the thread 
> terminates, the address space object is destroyed along with the 
> thread. Destroying the thread-with-discrete-address-space object has
> the side effect of disabling action points and decrementing the 
> reference counts on the SPU ELF image objects that were loaded into 
> the SPU thread's address space. I can now see why GDB would want 
> that event, and why TotalView would not.

OK.

> So, given that this is not a totally nutty request, is there a 
> formal "enhancement request" procedure that must be followed, or is 
> this something that this group will simply include in a future release?

Well, seeing as libspe is now maintained as an open-source project
open to contributions from everybody -- why don't you simply put 
together a patch against current mainline libspe (on sourceforge)
that solves your requirements, and post it to this list for the libspe
maintainers to have a look?


Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

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