Le dimanche 28 août 2011 à 22:23 +0200, "Martin v. Löwis" a écrit : > 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"). > > But those aren't used in iobench, are they?
I was not very clear, but you can change the encoding used in iobench by using the "-E" command-line option (while UTF-8 is the default if you don't specify anything). For example: $ ./python Tools/iobench/iobench.py -t -E latin1 Preparing files... Text unit = one character (latin1-decoded) ** Text input ** [ 400KB ] read one unit at a time... 5.17 MB/s [ 400KB ] read 20 units at a time... 77.6 MB/s [ 400KB ] read one line at a time... 209 MB/s [ 400KB ] read 4096 units at a time... 509 MB/s [ 20KB ] read whole contents at once... 885 MB/s [ 400KB ] read whole contents at once... 730 MB/s [ 10MB ] read whole contents at once... 726 MB/s (etc.) Regards Antoine. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
