Swiffies for...

DPBD

Although I'm not sure just how long Sun under Oracle can afford to crank out a product like this, but for the price VirtualBox is a pretty good piece of software, you just can't argue with free. I've been running it quite successfully on my frankenmac and it's been really, rock solid. Not sure about the speed as I haven't run VMWare nor Parallels.

http://www.productwiki.com/

although unbiassed reviews might be stretching it

Naked Mole Rats, once again!

http://news.yahoo.com/s/livescience/nakedmoleratssurviveextremeoxygendeprivation

Hey, there doesn't seem to be a fecal-chirp tag defined in HTML. How odd.

Am I totally l33t or what...

$ ./meanfilter_test --width=34
Mean Filtering Tester
=====================

CPU Version (Xeon W5580 @ 3.20GHz)

Filtering complete in 3.69872e+06 ms
Writing output file: cpublur.out



$ ./meanfilter_test_cuda --width=34
Mean Filtering Tester
=====================

Acquiring CUDA device
Using default device
CUDA device: Tesla C1060

Filtering complete in   136.063 ms
Writing output file: gpublur.out


$ vol_diff cpublur.out gpublur.out
No difference
$

I have no idea what any of that means so I'm gonna say yes.

YDD is showing us that, while his CPU takes a long time to render a specific blur function, his CUDA-enabled GPU (the hotshit NVidia Tesla) runs that specific blur function much much faster, with identical results.

Quote

while his CPU takes a long time to render a specific blur function

I take offense at that statement! ;-)

It's not my blur function, which is why I got the ludicrous speed up (on the order of 25,000x). I was given the CPU version - a bad implementation of an O(n³) algorithm, and told to make it run on the GPU. I changed it to an equivalent O(n) one when doing my CUDA version. Based on other tests, the GPU speed up is only about 30x (give or take a few PCIe transfers). All the rest of it comes from using an algorithm of much lower complexity.

Have you re-worked the bad implementation of the algorithm for the CPU as well to see how much improvement you'd get there?

Quote

Have you re-worked the bad implementation of the algorithm for the CPU as well to see how much improvement you'd get there?

No, although I have pointed out the problem in the bug tracking database (such as it is). Part of the problem is the arr[j][k] semantics which pervade the CPU code. For the rest.... it's C code which is trying to be templated, which means that there are switch statements all over the place. I generally prefer to avoid touching that without a very long pole.

I keep running into code like this:

if (computationally_complex_condition)
{
a = b;
}
a = b;


Who writes this stuff?

And I forgot to mention.... on the CPU side, some arrays are arr[j][k] while others are arr2[k][j]. Cache coherency anyone?

Quote
John Willoughby
Who writes this stuff?

Did you guys hire Wipro or something?

Actually, I got stuck doing code reviews for a newly acquired subsidiary whose products were having a lot of problems in the field. The horror... the horror...

Without code like that it would be too easy to spot the "rounding errors of a cent going to a secret account" sub routines, and without THAT neither Lex Luther nor the dudes from Office Space would have had a chance...

I especially love code like this, which was EVERYWHERE:

int8 retCode = NO_ERROR;

retCode = DoSomething();
retCode = DoSomethingElse();
retcode = DoYetAnotherThing();

if (retCode == ERROR)
{
return SOMETHING_WENT_WRONG;
}
else
{
return EVERYTHING_IS_SUPER;
}

How hard is the flaw here to see? I mean, people made a lot of money writing this code...

I hope that for a bugfix you suggested overloading the '=' operator so that if the LHS value was not NO_ERROR, the old value would be left ;-)

And some time I'll proofread before hitting 'post'



Edited 3 time(s). Last edit at 02/18/2010 10:29AM by YDD.

I don't favor overloaded operators for anything but very obvious usages. Too much confusion in group code. If they wanted that structure, they could have done something with |= and used different bits for different errors, but I'd have been happier if they just handled the errors as they detected them. Especially since some of the later functions depended on preceding functions completing successfully.



Edited 1 time(s). Last edit at 02/18/2010 11:08AM by John Willoughby.

Quote

I don't favor overloaded operators for anything but very obvious usages

But how're going to confuse people if you do that? I'd like to submit another little gem from the codebase I'm working on right now:

/*  compute the triple scalar product v1 x v2 . v3 */
float VectorTripleProduct( const VECTOR *v1, const VECTOR *v2, const VECTOR *v3)

Yes folks. The routine "VectorTripleProduct" does not, in fact, calculate the Vector Triple Product, but the Scalar Triple Product. Just a slight difference there....

Microsoft silverlight. A lot of streaming video sites use it now, including Netflix. And although Mac support lags on some of the latest features, the browser plugin is much less buggy and much more compact than Flash.

There's a neat site here in India called Burrp! which I came across when I was trying to find a good place to get local TV listings. I have been using it for a couple of weeks and noticed that vertical line they draw through the listing grid to show where the current time lines up was always slow by 10 minutes or so. I finally decided to click their Feedback link and told them that I found their site really useful and mentioned that I thought the clock might be off on their server. The next morning, the problem was corrected and today I got an email from them:

Quote

Hi,

Thanks a ton for your feedback and the great catch with the time lag. We have made the change. Please take a look and let us know if we're still not on track.

Thanks and regards,

Aarti Jesrani
Director - Content & Communications
burrp!
http://www.burrp.com/

That kind of friendly response is good for business. I've already recommended it to some of my colleagues here who didn't realize there was a place they could look up free TV listings in a convenient interactive grid like that without having to pay for digital TV service. I've also started poking around the rest of the site with their restaurant reviews, etc.