Message79338
Here is a patch to speedup utf8 decoding. On a 64-bit build, the maximum
speedup is around 30%, and on a 32-bit build around 15%. (*)
The patch may look disturbingly trivial, and I haven't studied the
assembler output, but I think it is explained by the fact that having a
separate loop counter breaks the register dependencies (when the 's'
pointer was incremented, other operations had to wait for the
incrementation to be committed).
[side note: utf8 encoding is still much faster than decoding, but it may
be because it allocates a smaller object, regardless of the iteration count]
The same principle can probably be applied to the other decoding
functions in unicodeobject.c, but first I wanted to know whether the
principle is ok to apply. Marc-André, what is your take?
(*) the benchmark I used is:
./python -m timeit -s "import
codecs;c=codecs.utf_8_decode;s=b'abcde'*1000" "c(s)"
More complex input also gets a speedup, albeit a smaller one (~10%):
./python -m timeit -s "import
codecs;c=codecs.utf_8_decode;s=b'\xc3\xa9\xe7\xb4\xa2'*1000" "c(s)" |
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Date |
User |
Action |
Args |
2009-01-07 15:25:04 | pitrou | set | recipients:
+ pitrou, lemburg |
2009-01-07 15:25:03 | pitrou | set | messageid: <1231341903.79.0.54860955311.issue4868@psf.upfronthosting.co.za> |
2009-01-07 15:25:02 | pitrou | link | issue4868 messages |
2009-01-07 15:24:59 | pitrou | create | |
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