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Category: Active Research
Forum: OpenPandemics - COVID-19 Project
Thread: Hyperthreading.... |
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Thread Status: Active Total posts in this thread: 53
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kapetan_proton
Cruncher Joined: Dec 10, 2008 Post Count: 37 Status: Offline Project Badges: 
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HT does produces more heat, but definitely outputs more work in terms of CPU time and work done per day. Using good cooler CPU can run for 24/7 without heat problems with HT on. Only exception to this would be if CPU needs double time to complete one WU with HT on or if it gets too hot or unstable using it.
----------------------------------------This is more important for laptops than desktops crunching machines. [Edit 2 times, last edit by kapetan_proton at Oct 16, 2020 2:07:51 PM] |
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kapetan_proton
Cruncher Joined: Dec 10, 2008 Post Count: 37 Status: Offline Project Badges:
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In my opinion, activating SMT does not have a real advantage for productivity. Depends on your goal. I'm using 3770K with HT on, stable on 4.5 GHz stock voltage under Noctua NH-D14, but mostly 4-4.3 GHz and I got almost double CPU time with HT on vs only 50% CPU load (similar to HT off scenario). Crunching times also shortens with 50% load, even if HT wasn't actually turned off, and Windows distributes load across all cores (real and virtual). CPU temps are pretty nice with that massive cooler. HT is useful if you chasing badges. In my case, it outputs more than 20% in term of CPU time per day. |
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Jean-David Beyer
Senior Cruncher USA Joined: Oct 2, 2007 Post Count: 339 Status: Offline Project Badges: 
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Rule of thumbs: If you run highly optimized code that does computation only, you most likely will not benefit from HT, at least not noticeable. I did some some experiments with fft stuff on 100gb data sets, using all that optimized math libs, and I never benefited from ht. All very well, but in distant history, when I was writing optimizers for the C compiler, even a program one would think compute-limited with floating point operations actually spent a huge amount of time doing fixed point operations; in particular, subscript calculations from the integers into the subscripts int arrays of floating point numbers.  |
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