Re: Should I enable or disable HyperThreading? [message #38523 is a reply to message #38511] |
Tue, 29 December 2009 07:14 |
gordan
Messages: 1 Registered: December 2009
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Junior Member |
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I cannot see HT harming OpenVZ performance (bugs notwithstanding). In general, HT will improve performance by:
1) Saving you half of the context switches (which is probably the most expensive operation you can do on a CPU)
2) Reduce the overall memory latency when things aren't in the caches. This is particularly helpful when you have lots of processes running on a machine. The latency to memory is typically around 50-60ns while latency to caches is typically 300-1000ps. If you have twice as many processes scheduled to run, the chances of the memory that at least one of them requires being correctly pre-fetched in the caches increases, so while one of them is waiting for the memory fetch the other can execute and get rotated back out.
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