GitLab

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.