[Haskell-cafe] Showing >100% CPU usage of parallel code

[Jim Burton]

Jeff Heard wrote:
> 
> Jim, I'm actually not sure that time will report greater than 100% cpu
> on ubuntu hardy. (really not sure, and don't have it available right
> this moment to check).  I would however try making a computation that
> will take a little longer and use the system monitor or /proc to look
> at your CPU usage rather than time.  I've had good luck with GHC 6.8
> using > 100% cpu, so I assume 6.10 will work much better.
> 
> 
Hi, thanks for that. The system monitor shows that I get ~160% usage, but
like you I don't know if it's possible to get time to display that (on
hardy, it clearly does elsewhere). The system monitor GUI is good enough, if
less neat than showing it via time. 

Jim


> 
> 
> On Sat, Feb 21, 2009 at 10:32 AM, Bulat Ziganshin
> <bulat.ziganshin at gmail.com> wrote:
>> Hello Jim,
>>
>> Saturday, February 21, 2009, 6:17:54 PM, you wrote:
>>
>>> main = a `par` b `par` c `pseq` print (a + b + c)
>>
>> two things:
>> 1) that are grouping order? may be,
>> a `par` (b `par` (c `pseq` print (a + b + c))) ?
>>
>> 2) i recommend you to use 2 *same* computations.
>> otherwise, it's easily possible that one of them needs much more time
>> that the rest
>>
>>
>>>     where
>>>         a = ack 3 10
>>>         b = fac 42
>>>         c = fib 34
>>
>>> fac 0 = 1
>>> fac n = n * fac (n-1)
>>
>>> ack 0 n = n+1
>>> ack m 0 = ack (m-1) 1
>>> ack m n = ack (m-1) (ack m (n-1))
>>
>>> fib 0 = 0
>>> fib 1 = 1
>>> fib n = fib (n-1) + fib (n-2)
>>> --------------------
>>
>>> Thanks,
>>
>>> Jim
>>
>>
>>
>>
>>
>> --
>> Best regards,
>>  Bulat                            mailto:Bulat.Ziganshin at gmail.com
>>
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