Author: Tom Kerrigan
Date: 13:06:28 04/14/03
Go up one level in this thread
On April 13, 2003 at 11:15:15, Robert Hyatt wrote: >On April 13, 2003 at 02:38:00, Tom Kerrigan wrote: > >>On April 13, 2003 at 01:03:17, Robert Hyatt wrote: >> >>>>You have been criticizing people for "bad math" this entire thread. You rejected >>>>the notion of a 50%-50% division: >>> >>>I didn't "reject" anything. I simply said it didn't match _my_ results and >>>it doesn't. I've already posted some results with wild variance. Separate >> >>Nonsense. Just read the quote I posted and you seemingly ignored: >> >>"But I don't buy the 50% stuff, the cpu is not that simple internally. One >>thread will run at nearly full speed and the other gets slipped into the gaps" > >And? That is based on _my_ testing with Crafty, as I said. IE it doesn't >happen that way for my _threaded_ application. I agreed that it _did_ happen >for totally independent processes, after I tested, because I don't normally >run that kind of test... Face it, you were making statements about the processor's architecture that were incorrect (remember the Cray YMP drivel you tried to use as some sort of supporting argument?). You obviously didn't realize that the CPU's resources were cleanly divided and now you're trying to pin this on some semantic "thread" vs. "processor" mumbo jumbo and saying that your numbers back you up, except that when you wrote the statements, you hadn't run any experiements at all (remember all the explanations about how running an experiment would be nearly impossible?) and didn't even know what your numbers were. And now that you have numbers, the most disparate being 70-30, they _don't_ back you up. If you get a 30% speedup from HT and one logical processor runs at full speed, that's 77-23 right there. Sure, you said "nearly" full speed, but you also didn't see a range as wide as 70-30 in all cases. >But it doesn't happen for the particular program that was the subject of this >thread, namely does SMT produce any _real_ speedup in Crafty. Data said How do you figure that? The root of this thread is 3.06 Xeon Test Results, the post that I referred you to, and that post doesn't even have the word Crafty in it. >>You go on to say that your assertion is supported by your results, but there is >>a big difference between saying "this is how things work and my results agree" >>and "my results indicate this is how things work." > >Again, look at the context of the entire thread. Not just the post you read. >It was about Crafty and SMT. That's why I ran the tests and posted the results. Again, no it wasn't. -Tom
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