Message boards :
Number crunching :
i7 v Core 2 curiosity.
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adrianxw Send message Joined: 14 Jul 99 Posts: 173 Credit: 1,698,756 RAC: 3 |
I don't know why I did it, but having done it, I noticed a curious thing. I crunched Workunit 2044507825, it ran very quickly. My machine, a 2.4GHz Core 2 crunched it in 57.20 CPU seconds. My wingman runs a 3.4GHz i7 and crunched it in 70.89 CPU seconds. Now, I would expect his more up-to-date faster CPU to run the job faster than me, not slower. Why would that be? Wave upon wave of demented avengers march cheerfully out of obscurity into the dream. |
archae86 Send message Joined: 31 Aug 99 Posts: 909 Credit: 1,582,816 RAC: 0 |
As boinc reports your machine has four CPUs, and the processor name implies it has four physical cores, it appears that you are not running hyper-threaded. So it took your machine 57.2 seconds to process the work unit on a single core which probably devoted very nearly all of its undivided attention to the task. Quite likely your quorum partner was operating hyper- threaded, which means that at the same time it spent 70.89 seconds completing the task while dividing its attention between two, it probably made similar progress on another task. In terms of effective throughput, quite likely the effectiveness was as though it spent 35.45 seconds doing the task in question. |
HAL9000 Send message Joined: 11 Sep 99 Posts: 6534 Credit: 196,805,888 RAC: 57 |
If you look at the Stderr output you will both of these tasks resulted in SETI@Home Informational message -9 result_overflow NOTE: The number of results detected equals the storage space allocated. Which are not really good results to compare. If you compare non overflow tasks you will find they average closer to 15,000 seconds for a task while you are averaging closer to 20,000 seconds. Looking at the actual Run time instead of just the CPU time there is much less difference. Run time CPU time 74.44 70.89 69.44 57.20 Another thing to note is since they are using their iGPU to process SETI@home work their CPU times are roughly double what they would be if using their CPU alone. SETI@home classic workunits: 93,865 CPU time: 863,447 hours Join the [url=http://tinyurl.com/8y46zvu]BP6/VP6 User Group[ |
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