Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!news-1.dfn.de!news.dfn.de!news.informatik.hu-berlin.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: blmblm@myrealbox.com Newsgroups: comp.programming.threads,comp.programming Subject: Re: Here is again my Proof Date: 18 Oct 2013 18:58:33 GMT Organization: None Lines: 55 Message-ID: References: <5256F730.1010009@toto.net> X-Trace: individual.net 4z01nn8DCw4Ob6nHhgtYZQqLFt1ScLU9/JBvhpLER0vV5sw1M7 X-Orig-Path: not-for-mail Cancel-Lock: sha1:WT2CtgTmCcvfQhZxqy9h4PB3VlQ= X-Newsreader: trn 4.0-test76 (Apr 2, 2001) Xref: csiph.com comp.programming.threads:1930 comp.programming:3942 In article , aminer wrote: > > I wrote: > > Hello, > > > > I think i know what is my mistake: the serial part in > > the Amdahl's law is not the critical section, you must not > > confuse the two. > Exactly. The serial part is the part that must be done exactly once and cannot be somehow split up among multiple threads or processes. > > But, Amine, how can you say that the serial part of the Amdahl's law is > not > the critical section ? Having got it right once (above), why now go off the rails again (below) .... (And why start a new thread for each new thought, rather than keeping the whole discussion in one thread?) > In my example if you don't have context switches , and you have the same > number of threads than the number of cores, and the time inside the > critical > section is constant and the time inside the parallel part is constant, > so the Amdahl's law can predict the worst case contention scenario , > that means when all the threads are contending for the same critical > section, hence you can predict the worst case contention scenario by > just calculating the time inside the critical section and the time > inside the parallel part and doing the Amdahl calculation, this will > give you the > exact result for the worst case contention scenario, so as you have > noticed the serial part of the Amdahl equation is not only the critical > section, it's the critical section with a context, so you have to take > into consideration also the context, that means the context of the worst > case contention scenario. > > > Thank you, > Amine Moulay Ramdane. > > > [ snip ] -- B. L. Massingill ObDisclaimer: I don't speak for my employers; they return the favor.