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On Tue, 14 Jul 1998, Linus Torvalds wrote: > On Tue, 14 Jul 1998, Gerard Roudier wrote: > > > > If your program seems to demonstrate that having even up to 5% memory > > free does not help a lot and that the ratio of pages you will throw away > > No, read the math again. > > The only reason I wrote a program to do the calculations was that I was > too lazy (and possibly too inept) to symbolically solve the value of > > x * (x-2) * (x-4) * .. (y times) > ----------------------------- > x ^ y > > so I just wrote a program to iterate and do the calculations for me. > > Having 5% memory free almost guarantees that you'll have consecutive pages > for an 8MB machine. It also showed very clearly that on a 4MB machine it > was getting painful - you needed to keep a fair amount of your memory free > to give the same kinds of guarantees. This perhaps _almost_ guarantees that you will succeed the allocation _once_, but the problem is to _almost_ guarantee that you will succeed _most_ of the time. Basically, if a probability of 0.99 _almost_ guarantees you will succeed _once_, it also _almost_ guarantee you will _fail_ _once_ for 100 tries. At a raw approximate, if P is the probability to succeed once, the probability to succeed N times consecutivevely is P at the power of N. Note that my simulation was broken this way too. Regards, Gerard. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.altern.org/andrebalsa/doc/lkml-faq.html | ||||||||||||
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