cwinl wrote: > my server is dual P4 Xeon 2.8G with HT tech. > someone told me that i should turn off HT because of bad performance. > i'd never heard about that before. > is it a good advice and worth to do that right now?
What I really recommend is that you should benchmark your system and determine that for yourself. Run first one task. Then two tasks simultaneously. Then three and so on. Try that both with hyperthreading on and then with it off. What I found is that the first two logical cpus were on the same physical cpu. So two running tasks would be located there. Each would run at half speed because they each get only half of a physical cpu. The other cpu in the dual cpu system would be idle until a third task came along at which it would run that task at full speed. Hyperthreading was actually hurting a multi-cpu system because the kernel task scheduler did not know about it. This was with linux 2.4 and I do not know if 2.6 improves upon the situation. Bob
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