[Haskell-cafe] Questions about slow GC with STArray

Bulat Ziganshin bulat.ziganshin at gmail.com
Mon Apr 6 04:47:06 EDT 2009

Hello Dan,

Monday, April 6, 2009, 12:35:14 PM, you wrote:

> the size of the sub-array. The test then fills a 10 million element array.

> However, something about the benchmark makes it perform poorly for both small
> chunks and large chunks. -sstderr reports that lots of copying occurs for
> small chunk sizes, and I haven't bothered to figure out why this is the case.
> You can, however, see that marking dirty chunks in this fashion would be
> profitable. The un-chunked array takes around a minute here, while with chunks
> of 10,000 (which seems to be about the optimal value with the above copying
> tradeoff), it takes about 6 seconds, and that's still with 60+% GC time.

i don't think that 60% GC time is bad for *this* benchmark. array
filling is very trivial operation, after all. important part is 10x GC
times reduce, apply these numbers to original benchmark

Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com

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