[MLton] follow-up [cost of _export]

On 12/08/14 22:42, Bernard Berthomieu wrote:
> I will try the patch asap and let you know the
> improvements on my use case.

Could not wait :-) .

The experiment consists of parsing a 16MB xml file.
There are 1 011 136 calls from C to SML.


gc-summary before the patch:

GC type        time ms     number          bytes          bytes/sec
-------------    -------    -------    --------------- ---------------
copying         13,720        775      2,123,511,788 154,774,913
mark-compact          0          0                  0               -
minor              0          0                  0 -
total time: 27,121 ms
total GC time: 20,487 ms (75.5%)
max pause time: 313 ms
total bytes allocated: 14,275,417,936 bytes
max bytes live: 22,243,940 bytes
max heap size: 178,012,160 bytes
max stack size: 10,384 bytes
...

The total time drops to 8s with "fixed-heap 1G", but rises to
500s (99% of which in gc) with "copy-generational-ratio 8.0"
(default for my applications) with a huge amount of minor gc.


gc-summary after the patch:

GC type        time ms     number          bytes          bytes/sec
-------------    -------    -------    --------------- ---------------
copying            289         12         48,134,248 166,554,491
mark-compact          0          0                  0               -
minor              0          0                  0 -
total time: 2,362 ms
total GC time: 519 ms (22.0%)
max pause time: 200 ms
total bytes allocated: 225,872,036 bytes
max bytes live: 20,448,692 bytes
max heap size: 163,635,200 bytes
max stack size: 8,776 bytes
...

Total time drops to 1.87s with "fixed-heap 1G" and stays
unchanged with "copy-generational-ratio 8.0" (no minor gc
is triggered).

A cheap _export opens up new perpectives :-)

Best,
   Bernard.


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