[Python-Dev] PEP 393 review

["Martin v. Löwis"]

Am 28.08.2011 22:01, schrieb Antoine Pitrou:
> 
>> - the iobench results are between 2% acceleration (seek operations),
>>   16% slowdown for small-sized reads (4.31MB/s vs. 5.22 MB/s) and
>>   37% for large sized reads (154 MB/s vs. 235 MB/s). The speed
>>   difference is probably in the UTF-8 decoder; I have already
>>   restored the "runs of ASCII" optimization and am out of ideas for
>>   further speedups. Again, having to scan the UTF-8 string twice
>>   is probably one cause of slowdown.
> 
> I don't think it's the UTF-8 decoder because I see an even larger
> slowdown with simpler encodings (e.g. "-E latin1" or "-E utf-16le").

Those haven't been ported to the new API, yet. Consider, for example,
d9821affc9ee. Before that, I got 253 MB/s on the 4096 units read test;
with that change, I get 610 MB/s. The trunk gives me 488 MB/s, so this
is a 25% speedup for PEP 393.

Regards,
Martin