Quote:
Originally Posted by
nytty
At the application level page size is an important concept, it's the unit of interaction with the disk.
Agreed.
However, you're not actually interacting with the raw disk in your tests. You're telling the OS to do so for you, which does as it pleases. It will turn a tiny read into a much larger read for you -- ruining your results.
Even the OS isn't dealing with the disk raw, here. The OS asks the disk and the disk does what it pleases, pulling things from its own cache -- ruining your results.
Not to mention, you're running huge programs to do tiny things, which drowns your numbers in meaningless noise -- ruining your results.
Too bad there's not a program that actually deals with disks the way you want already... Something which can tell you transfer rates, bus modes, and bus speeds. Something which can configure software
and hardware read-ahead, flush hardware caches at will, and all that jazz, letting you compare results for different configurations. Something which you can actually tell 'read raw sector x', and it will do so.
They really ought to make a program like that.
I bet they'd call it hdparm.
