NOTE: This patch has been committed. The version below is informational only (whitespace differences have been removed). ChangeLog addition: 2006-01-09 Didier Verna <didier@lrde.epita.fr> * 2.0/README: Update comments for dedicated versions. GSC source patch: Diff command: svn diff --diff-cmd /usr/bin/diff -x "-u -t -b -B -w" Files affected: 2.0/README Index: 2.0/README =================================================================== --- 2.0/README (revision 46) +++ 2.0/README (working copy) @@ -161,23 +161,32 @@ ** src/dd -dedicated code, no abstraction +*** Languages currently used: +C, Java, Eiffel, Common Lisp. -*** comments - -the C code gives us a time reference. - -*** code - -c/ - dd_c.c - -java/ - Main.java - -eiffel/ - image1d_int.e - main.e +*** Comments: +Programs are fully dedicated (no abstraction). Apart from language-specific +peculiarities, there are 4 variations of the algorithm for each language: +- images represented as one or two-dimensional arrays +- linear or "randomized" image traversal + +The linear versions simply traverse the images by line / column order. The +"randomized" versions (files ending with an 'i') are supposed to minimize the +hardware / os impact on memory access (typically, cache size, pagination etc). +To this aim, image traversal is done by column first (in 2D array versions), +and individual cells are accessed by steps of a prime number. + +Along with the same lines, the default image size (800) is chosen *not* to be +a power of two. + + +Some recommendations: +- do not use language-specific idioms (e.g. *p++ = ... in C) to avoid + potential language-specific optimization. We want to test the algorithm + only. +- do not bench on a single run of the algorithm, to avoid initalization + artefacts (like initial page faults), and timing precision influence. That's + why the default number of runs is set to 200. ** src/st -- Didier Verna, didier@lrde.epita.fr, http://www.lrde.epita.fr/~didier EPITA / LRDE, 14-16 rue Voltaire Tel.+33 (1) 44 08 01 85 94276 Le Kremlin-Bicêtre, France Fax.+33 (1) 53 14 59 22 didier@xemacs.org