Removing code slows down inner product
| Bugzilla Link | 160 |
| Created on | Nov 26, 2005 23:32 |
| Resolution | INVALID |
| Resolved on | Nov 29, 2005 11:55 |
| Version | 1.00beta |
| OS | Linux |
| Architecture | PC |
| Attachments | ipbbslow.sac |
Extended Description
ipbbslow.sac runs MUCH slower if you remove the trailing +/+/ from the code. This is a Boolean matrix product algorithm, which generates a fairly large (400x400) result. In order to get a rough idea of whether the code is producing anything close to the right result, I sum the result rows and then sum that result, to produce a scalar. Now, here's the fun part: 1.If you run the code without the +/+/, it runs quite quickly (1.25 seconds). 2.If you run the code WITH the +/+/, it runs extremely slowly (several minutes). The interesting fact is that, based on "print" statements, the thing that is taking a long time not the +/+/, but the inner product that precedes it, and that just ran really quickly. I was going to make conjectures about the cause, but think I'll just go have dinner instead.