Avi Kivity wrote:
This will overflow. I think that
currentPos = drand48() * s.st_size;
will give better results
currentPos=currentPos%s.st_size;
why would it overflow? Random() returns a 32 bit number, and if I
multiple that by 32k (basically the number random() returns is the block
number I am going to), that should never be over 64 bits? It may be over
to size of the file though, but that is why I do mod s.st_size... and a
random number mod something is still a random number. Also, with this
method it is already currentSize aligned...
Sorry, I wasn't specific enough: please run iostat -x /dev/whatever 1
and look at the 'r/s' (reads per second) field. If that agrees with what
your test says, you have a block layer or lower problem, otherwise it's
a filesystem problem.
I ran it and found an r/s at 165, which basically corresponds to my 6 ms
access time... when it should be around 3.5ms... so it seems like the
seeks themselves are taking along time, NOT that I am doing extra seeks...
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