Messages in this thread | | | Subject | Re: Interesting analysis of linux kernel threading by IBM | Date | Sun, 23 Jan 2000 10:12:29 -0800 | From | Larry McVoy <> |
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: > No, yet again the _app_ design you propose is the bottleneck. : : I'll respect Your opinion but the mine is different.
I spent the day yesterday cutting down a tree (a college era skill I aquired, long story), so I just went through all the mail on this thread.
Somebody, apologies for not remembering who, said this is turning into a "he said, she said" type of argument and I have to agree.
At this point, Davide, it has been made clear that there are a number of people who have experience and are saying that your approach has a strong chance of being, err, less than optimal. You and the other fix-the-scheduler people seem pretty insistent that it is the right thing to do.
The other side is saying ``this application design will yield poor performance, and in general, we believe that the right number of active processes or threads is N | N == #CPUS perhaps plus a small number of controller threads.''
Given that there is enough controversy on both sides, and that you want the scheduler to change over the objects of a number of experienced people who believe that it's a bad idea, I think it is reasonable to ask that you demonstrate that your application does indeed perform better with your model. So please code up a pair of benchmarks, one which does all the work in one thread (but can have N concurrent threads running) and one that does the work in the pipeline. If you can show that the model you propose has _BETTER_ performance than the other model, then there is indeed a good reason to consider the scheduler changes. If the performance is worse, or even the same, then there really is not much reason to make any changes. If the performance were the same in both cases, you could argue that the threaded model has a nicer programming model and we should support it. Let's cross that bridge when we come to it, the first step is to get the benchmarks.
I strongly feel that since you are pushing for this, the benchmarks are something you need to do. You are perfectly qualified to do them because you understand your application, and I at least, apparently don't. So please come forward with the benchmarks and the results and until then, let's drop this topic. I think we've pushed it as far as we can in this forum. Any objections from anyone?
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