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Number crunching :
Random Musings About the Value of CPUs vs CUDA
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Francois Piednoel Send message Joined: 14 Jun 00 Posts: 898 Credit: 5,969,361 RAC: 0 |
Keep trying ... Show the best you can get ... |
Voyager Send message Joined: 2 Nov 99 Posts: 602 Credit: 3,264,813 RAC: 0 |
That's all well and good, but you must have the APunits to crunch along with cuda.I haven't gotten any APs so with my cuda alone doing Mbs I figure a wall rac of ~2764.Thats just using one core to feed with one idle.It would be very hard to get enought APs to get high rac.If I put it on my quad I have 3 cores doing nothing.. |
mr.kjellen Send message Joined: 4 Jan 01 Posts: 195 Credit: 71,324,196 RAC: 0 |
At the time before I put CUDA on it wasn't on 24/7...more like running daytime...then RAC was at around 4000. It hit a high at around 6K when running flat out 24/7. Too bad the AP Validator is acting up. I was hoping the RAC woul level out soon. Judging from a look at boinc stats, north of 10K. /Anton |
Alinator Send message Joined: 19 Apr 05 Posts: 4178 Credit: 4,647,982 RAC: 0 |
Thanks for that intel, Anton. That's not too shabby a gain for bringing the GPU online. ;-) One more question here, which should help put a lot of this to bed once and for all. We can see accurate info for the CPU tasks (both AP and MB) and thus can calculate the CPCS(HR) for the host ourselves for them. However, we can't do this for CUDA currently. So if you would be so kind, what would your 'best guess' estimate for the average Total Task Execution Time for CUDA. For this purpose, we will define this as the total Wall Time BOINC had the CUDA task executing for (don't forget it might get swapped out, thus start in one time slice and finish in another). We'll call it CPGS (for GPU, obviously). Granted this puts the CPU at a slight disadvantage, since we are assuming CUDA always gets all the GPU all the time when it's running. Obviously, it can't, since the card might still get called upon once in while to actually perform it primary function. However, for hard core, dedicated crunchers, this is a reasonable assumption for this exercise. Now contrary to what some would like us to believe, we can now evaluate the true measure of absolute sheer performance, the average per task CPCS. I was scanning over Mark's Frozen Nehi. Let's say, for the sake of argument, it's pulling in the low 60's for Credit per Hour per core (CPCS= ~.0175) overall. So there is a baseline to shoot for when comparing to the current CPU state of the art. The simple truth is that RAC is nice to use for bragging purposes, and rough performance 'health' indicator for a host, but is close to worthless as a true performance metric. @ Richard: I don't know if you where calculating this, but if you were, what did you get for an 'effective' CPGS on your test run? Alinator |
mr.kjellen Send message Joined: 4 Jan 01 Posts: 195 Credit: 71,324,196 RAC: 0 |
There is lots of manual work involved in investigations like tihs, and it would help a >LOT< if we had a value in the results describing GPU time...then it would be a trivial matter for Fred to bring out his DATAVAC excel file and examine the output. I can say this however. The times I counted there were ~320-330 files reported during a 24 hour period. I looked at my cache and got these timings for you for som different ARs AR 3,3 01/17/09 09:49:06|SETI@home|Starting task 05no08ad.18070.11934.9.8.236_0 01/17/09 09:53:44|SETI@home|Computation for task 05no08ad.18070.11934.9.8.236_0 finished AR 0.79 01/16/09 21:24:38|SETI@home|Starting 08no08aa.14123.1300.4.8.217_2 01/16/09 21:32:43|SETI@home|Computation for task 08no08aa.14123.1300.4.8.217_2 finished AR 0,467 01/17/09 01:14:20|SETI@home|Starting task 14no08af.21130.9479.12.8.165_25 01/17/09 01:24:45|SETI@home|Computation for task 14no08af.21130.9479.12.8.165_2 finished AR 0,378 01/17/09 06:20:12|SETI@home|Starting task 02no08ac.31941.23385.10.8.38_0 01/17/09 06:32:20|SETI@home|Computation for task 02no08ac.31941.23385.10.8.38_0 finished AR 0,12 01/17/09 01:24:45|SETI@home|Starting 08no08ab.14807.78154.8.8.96_2 01/17/09 01:42:27|SETI@home|Computation for task 08no08ab.14807.78154.8.8.96_2 finished Hope that helps...gotta run. /Anton |
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