Messages in this thread | | | Date | Wed, 19 Sep 2007 23:30:10 +0200 | From | Andi Kleen <> | Subject | Re: A little coding style nugget of joy |
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> This is a terrible assumption in general (i.e. if filesize % blocksize > is close to uniformly distributed). If you remove one byte and the data > is stored with blocksize B, then you either save zero bytes with > probability 1-1/B or you save B bytes with probability 1/B. The > expected number of bytes saved is B*1/B=1. Since expectation is linear, > if you remove x bytes, the expected number of bytes saved is x (even if > there is more than one byte removed per file).
You didn't calculate the probability of actually saving a full block or not (that's the only thing that matters). I assumed it's relatively small and can be ignored in practice since the amount of end white space is negligible compared to total file size.
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