Distributed SETI and Hyperthreading

Has anyone had any experience running SETI on an Intel "Hyperthreaded" system. I know that dual processors give good results but was curious if dual logical processors helped reduce WU times.

 

I ran Seti on a HT system, with HT and without HT. Without HT times were about 3 hours. With HT I had to run two instances of Seti, one for each proc, and times for individual WUs were about 4 hours. So I had the option of 1 every 3 hours, or 2 every 4 hours. (2 every four hours averages to about 1 every two hours.)

YMMV, as this was about six months ago, and your system is likely better than the one I used.

 

Spike runs two instances of SETI on his HT chip IIRC

 

You have to run a seperate instance of SETI for each processor or virtual processor (SMP vs. HT) I think, as the SETI dev team has not been able to take advantage of multi-processing yet.

 

To be honest, they don't need to take advantage of SMP. As running a client on each CPU gives about a 5% drop over what the processor would get in a single processor system. So, it's a toss up of whether running two at once is better than running one very fast, which would be the result of real SMP seti crunching.

 

But SETI only uses the FPU right? And the HT processor isnt a true "dual" so it only has 1 FPU unit?

 

HT takes the times when vCPU1 is waiting for data, and makes vCPU2 work, and switches them. This way the CPU is always recieving data, and always working on it. The real problem with it is that there is only 1/2 of the normal cashe for each virtual CPU.

I haven't really read up on the HT P4s though, so I may be wrong.

 

I've never been able to get the exact times with one and two instances running on my 2.4c@3.2 w/ h/t since it was going towards my account which had a bunch on units already and you can't run two with the graphical version, but as it should be doing two units at the same time, it should go around twice as fast. Again I don't have the numbers to back that up... there's no great way to record the CLI version's time per unit.

 

Firehed, Setistash will show WU times for up to 50 stored units. (untill you transmit them) You can also run two instances from the same installation.

http://forums.bit-tech.net/showthread.php?t=37387 <--- That URL contains installation instructions.

 

hehe I was using a different loader thing, that's why. can't remember the name for the life of me though... my temps were getting a little warm during the summer (as was my room!!)

 

hehe I was using a different loader thing, that's why. can't remember the name for the life of me though... my temps were getting a little warm during the summer (as was my room!!)

"Spike runs two instances of SETI on his HT chip IIRC"
If you don't mind me asking... what does IIRC stand for? It's been driving me nuts for a while...

 

IIRC = If I Recall Correctly

 

When I was crunching SETI@home (before moving to BIONC), my P4 system would be running SETIbuffer which would automatically run 2 instances of SETI CLI. As the guy posted above, with HT enabled, the units/hour rate does increase slightly.