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List: haskell-cafe
Subject: RE: [Haskell-cafe] using Map rather than FiniteMap
From: "S. Alexander Jacobson" <alex () alexjacobson ! com>
Date: 2005-01-26 14:28:58
Message-ID: Pine.WNT.4.61.0501260848511.2544 () philo
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Ah, ok. So I ran the code with 100000 items,
50000 items, and 25000 items and got total memory
in use of 28Mb, 15Mb, and 8Mb respectively. That
comes to 260-280 bytes per record which is still
an order of magnitude higher than the 20-30 bytes
per record we would expect.
On the other hand, I found 10mb, 5mb, and 2.5mb
maximum residency, but that is still ~100 bytes
per record.
Lastly, I tried "example +RTS -p -K5M -hc" and
then looked at the resulting graph (attachment #2)
and it shows a total of 1.6Mb heap allocated and
if that data is correct, it does correspond
roughly to our 20-30 bytes per record estimate.
Regarding stack, I tried "example +RTS -p -K5M -xt
-hc" and then ran hp2ps and looked at the
resulting graph (attachment #1) SYSTEM appears to
use 4mb of stack at the very beginning (presumably
to create "zipped"), but I don't know why it
would. Then this stack is consumed by the rest of
the program.
Can you provide some guidance on interpreting this
data?
-Alex-
______________________________________________________________
S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com
On Wed, 26 Jan 2005, Simon Marlow wrote:
> On 25 January 2005 23:27, S. Alexander Jacobson wrote:
>
>> Oops. It pays to check your checking code before
>> making posts like this.
>>
>> After actually running the correct test, I am
>> still getting semi-ridiculous space behavior
>> (6k/pair)!
>>
>> import qualified Map
>> zipped =zip [1..] [1..100000]::[(Int,Int)]
>> untup f (x,y) = f x y
>> produce = foldr (untup Map.insert) Map.empty zipped
>> fm = length $ Map.keys produce
>> main = print $ fm
>>
>> Has this profile:
>>
>> example +RTS -p -K5M -RTS
>>
>> total time = 5.10 secs (255 ticks @ 20 ms)
>> total alloc = 612,534,236 bytes (excludes profiling overheads)
>>
>> COST CENTRE MODULE %time %alloc
>> balance Map 71.8 72.8
>> insert Map 12.2 10.8
>> size Map 9.0 9.7
>> bin Map 2.4 2.2
>> rotateR Map 1.6 0.3
>> zipped Main 0.8 1.9
>>
>> Notice the 612Mb for storing a mapping from Int
>> to Int!!
>
> Notice that's 612Mb *allocation* to create the finite map and
> deconstruct it into a list. Not 612Mb of live heap to store the finite
> map. If you make sure everything is evaluated, and examine the heap
> profile I'm sure you'll find that the finite map is taking a reasonable
> amount of space (perhaps 20-30 bytes per node for storing integers, I
> guess).
>
> To get a rough idea of the total live heap without profiling, you can
> run the program with +RTS -sstderr and look at the memory "in use"
> figure.
>
> Cheers,
> Simon
>
["example.ps" (APPLICATION/POSTSCRIPT)]
["example2.ps" (APPLICATION/POSTSCRIPT)]
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