[vsipl++] [patch] Tunable parameters

[Jules Bergmann]

Stefan,

> OK. (For avoidance of doubt: this remains a very evaluator-specific 
> function, so this wouldn't become part of the generic Evaluator 
> interface, right ?)

Yes, the evaluator needs to check the right size against the threshold 
in its rt_valid.  Choosing a consistent name for the function that 
generates the threshold is just a convenience, not a requirement.


> I think the high-order bit to capture in a comment is the tuning 
> process, from 300000 feet:
> Compile with VSIP_IMPL_TUNE_MODE=1, and then find the cross-over problem 
> sizes by comparing benchmark runs with 0 and N SPEs.
> 
> I think 'tunable_threshold' is better than any alternative I can come up 
> with.

Ok, sounds good.  I'll put the following in config.hpp (near the 
TUNE_MODE define):

// Setting TUNE_MODE to 1 disables the tunable_thresholds.  This
// allows benchmarks to be run without thresholds to determine
// cross-over points, whcih can then be used as thresholds.

Near thresholds, I'll put something like:

// Compare interleaved vmul -2 --svpp-num-spes {0,8}.

to indicate that 'vmul -2 --svpp-num-spes 0' and 'vmul -2 
--svpp-num-spes 8' should be compared, with interleaved complex, to 
determine the threshold.

				-- Jules

-- 
Jules Bergmann
CodeSourcery
jules at codesourcery.com
(650) 331-3385 x705