[Haskell-cafe] Re: Hugsvs GHC (again)was: Re: Somerandomnewbiequestions

Keean Schupke k.schupke at imperial.ac.uk
Wed Jan 19 11:48:39 EST 2005

Duncan Coutts wrote:

>If it's just a question of speed then the fastest IO system is the
>variety that GHC uses now: a single OS thread that multiplexes all IO
>requests using a select loop.
But what about the continuing computation... we do not want
the fastest IO system, but we want the program to comlete the
fastest... So ideally we want 2 threads!

One runs the Haskell code that is not waiting for IO. (IE other
Haskell threads)... The other runs a select loop as you suggest!

This way the number of threads is fixed (2) and execution never
'blocks' for IO. (Simon, what about this scheme?)

>If you have more than one CPU you would want more than one OS thread.
>The number of threads should scale with the number of CPUs not the
>number of Haskell threads that want to do IO.
I completely agree with this, but obviously I would suggest 1 thread
per CPU, (maybe 2 including a garbage collector) plus an additional
thread on the CPU attached to the IO bus to do IO.


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