PIV Hyperthreading question?
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Number crunching :
PIV Hyperthreading question?
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 AndyW   Send message Joined: 23 Oct 02 Posts: 5862 Credit: 10,957,677 RAC: 18 
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If I run a machine that has hyperthreading capability with the hyperthreading edisabled will it crunch a WU twice as fast as it would if hyperthreading was enabled and it was crunching 2 units? I've tried doing comparisons, but without a set of identically sized WUs to play with it's hard to come up with the answer. ID: 718730 ·  |
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Alinator Send message Joined: 19 Apr 05 Posts: 4178 Credit: 4,647,982 RAC: 0 
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The host will crunch faster with HT disabled, but not twice as fast. IIRC, you gain about 40% or so more total throughput with HT enabled, but I forget what the folks were posting the observed increase in individual task runtime was. HTH, Alinator ID: 718731 · |
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AndyW Send message Joined: 23 Oct 02 Posts: 5862 Credit: 10,957,677 RAC: 18
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OK, so there is a gain using hyperthreading for our purposes. Thank you. I can see where it wouldn't always be useful, but for number crunching it seems to fit well. Thanks for your answer. ID: 718733 · |
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tfp Send message Joined: 20 Feb 01 Posts: 104 Credit: 3,137,259 RAC: 0
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It will not be twice as fast but normally it will add 20-40% vs running just one. ID: 718734 · |
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Alinator Send message Joined: 19 Apr 05 Posts: 4178 Credit: 4,647,982 RAC: 0
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It will be interesting to see how well Intel addressed the shortcomings with HT when they rollout the 2nd generation of it in Nehalem. Alinator ID: 718737 · |
Keck_Komputers  Send message Joined: 4 Jul 99 Posts: 1575 Credit: 4,152,111 RAC: 1
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It will be interesting to see how well Intel addressed the shortcomings with HT when they rollout the 2nd generation of it in Nehalem. I wonder if they even recognise any shortcommings with HT. It was designed to find hidden performance in the CPUs and it did find about 15% to 30%. BOINC WIKI   BOINCing since 2002/12/8 ID: 718985 · |
Misfit  Send message Joined: 21 Jun 01 Posts: 21804 Credit: 2,815,091 RAC: 0
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The answers here are correct. Various projects will give different results. For best results always leave H/T on and crunch two different projects at the same time. Having two instances of the same project running will have them competing for the same resources at the same time. It will be interesting to see how well Intel addressed the shortcomings with HT when they rollout the 2nd generation of it in Nehalem. I was thinking about that myself. 16 cores anyone? me@rescam.org ID: 718988 · |
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