[Haskell-cafe] Re: System.CPUTime and picoseconds

ChrisK haskell at list.mightyreason.com
Sat Jan 10 18:06:13 EST 2009

Manlio Perillo wrote:
> Hi.
> Just out of curiosity, but why Haskell 98 System.CPUTime library module 
> uses picoseconds instead of, say, nanoseconds?
> At least on POSIX systems, picoseconds precision is *never* specified.

I have not idea.  But at a guess, I would say that 1 ns is not such a small time 
interval anymore.  The CPU speeds are about 3 GHz, so 0.3 ns per CPU clock. 
Even the RAM clock in a laptop (e.g. Apple's 17" Mac Pro) is 1066 MHz, so the 
internal there is just under 1 ns.

Whoever picked picoseconds has made it possible to talk about a single clock 
interval for hardware like this.


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