| Message ID | 4C0DEF94.5020404@kit.edu |
|---|---|
| State | New |
| Headers | show |
On 8 June 2010 08:21, Johannes Singler wrote: > This patch corrects the calculation of the part lengths for parallel > partial_sum, leading to the expected behavior for > partial_sum_dilation!=1, and thus better performance. > > Tested x86_64-unknown-linux-gnu: No regressions. > > Please approve for mainline. > > 2010-06-08 Johannes Singler <singler@kit.edu> > > * include/parallel/partial_sum.h > (__parallel_partial_sum_linear): > Correctly calculate part lengths for partial_sum_dilation!=1. Please declare each variable on its own line, as per http://gcc.gnu.org/onlinedocs/libstdc++/manual/source_code_style.html char* c = "abc"; // each variable goes on its own line, always. (Unfortunately the coding style guide seems to have got mangled by the conversion to docbook, I'll fix that.)
Index: include/parallel/partial_sum.h =================================================================== --- include/parallel/partial_sum.h (revision 160253) +++ include/parallel/partial_sum.h (working copy) @@ -127,10 +127,12 @@ equally_split(__n, __num_threads + 1, __borders); else { - _DifferenceType __chunk_length = - ((double)__n - / ((double)__num_threads + __s.partial_sum_dilation)), - __borderstart = __n - __num_threads * __chunk_length; + _DifferenceType + __first_part_length = std::max<_DifferenceType>(1, + (float)__n / + (1.0 + __s.partial_sum_dilation * (float)__num_threads)), + __chunk_length = (__n - __first_part_length) / __num_threads, + __borderstart = __n - __num_threads * __chunk_length; __borders[0] = 0; for (_ThreadIndex __i = 1; __i < (__num_threads + 1); ++__i) {
This patch corrects the calculation of the part lengths for parallel partial_sum, leading to the expected behavior for partial_sum_dilation!=1, and thus better performance. Tested x86_64-unknown-linux-gnu: No regressions. Please approve for mainline. 2010-06-08 Johannes Singler <singler@kit.edu> * include/parallel/partial_sum.h (__parallel_partial_sum_linear): Correctly calculate part lengths for partial_sum_dilation!=1. Johannes