[BitTorrent] BT2 & hash trees

}T{Reme [Q_G] applsapff xtremeq_g at hotmail.com
Fri Jul 23 08:34:46 EDT 2004


> > to calculate some hash? If it reduces the load on the servers, so be it.
> > (within limits of course, no point having a user's computer
>number-crunching
> > so much it becomes unresponsive)
> >
> > To be honest, you hashed 4 gb of data. Part of that time is being used 
>for
> > retrieving the data from the hard disk. Unless you believe it 
>miraculously
>
>Just reading data doesn't take that much CPU time.
>

Yes I agree. Altho as far as I can tell those are total run times. Not total 
cpu time. Average drives can only read 30-50 megs a second. A little math 
tells that about 41 to 68 percent of that time was added for calculating the 
hash. As far as I can tell, a program is frozen during a read operation on a 
file (waiting for data, not doing anything) unless the test program was 
using seperate threads to allow the calculation to continue while data was 
being retrieved.  You can more or less assume that half of the time was 
spent in a blocked state and the other processing. More acurate testing 
could be done by hashing a pre-generated block of junk over and over.

This does go a bit beyond the point tho...

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