[PATCH -- RFC] Add support OProfile for profiling Cell BE SPUs

[Maynard Johnson]

The attached patch extends OProfile's Cell support (committed into 
2.6.20-rc1), adding the capability to do time-based profiling of the SPUs.

This is a preliminary patch we're posting for comments.  Development is 
not 100% complete yet, but very close.  This patch is dependent on two 
outstanding patches that have not yet been committed to mainline:  1) 
the cleanup patch for the initial OProfile Cell PPU support (posted on 
Nov 27); and 2) the spu notifier patch (posted on Dec 1), which exports 
the [un]register functions in SPUFS.  It is also dependent on an 
internal patch, which will be submitted once the cleanup patch is 
committed.  So please don't try to apply this patch to a source tree yet.

The code is functional and passing all test scenarios, except one:  if 
an SPU task is already active before OProfile is started, the 
notification we receive for this already-active task happens in the 
wrong context, so we're unable to collect the information we need about 
the SPU binary being executed.  The spu notifer patch mentioned above 
was meant to solve this problem, but in fact, it does not (which is why 
that patch hasn't been committed yet).  We're currently investigating
other options.

All comments are welcome.

NOTE:  The availability of the developers of this patch is limited 
between now and Jan 2, 2007, so replies to comments may be delayed until 
then.

Thanks.
Maynard Johnson
IBM LTC Toolchain
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