[Python-Dev] PATCH submitted: Speed up + for string concatenation, now as fast as "".join(x) idiom

[Kristján V. Jónsson]

This patch looks really nice to use here at CCP.  Our code is full of string contcatenations so I will probably try to apply the patch soon and see what it gives us in a real life app.  The floating point integer cache was also a big win.  Soon, standard python won't be able to keep up with the patched versions out there :)

Oh, and since I have fixed the pcbuild8 thingy in the 2.5 branch, why don't you give the PGO version a whirl too?  Even the non-PGO dll, with link-time code generation, should be faster than your vanilla PCBuild one.  Read the Readme.txt for details.

Cheers,

Kristján
 

> -----Original Message-----
> From: python-dev-bounces+kristjan=ccpgames.com at python.org 
> [mailto:python-dev-bounces+kristjan=ccpgames.com at python.org] 
> On Behalf Of M.-A. Lemburg
> Sent: 9. október 2006 09:30
> To: Larry Hastings
> Cc: python-dev at python.org
> Subject: Re: [Python-Dev] PATCH submitted: Speed up + for 
> string concatenation, now as fast as "".join(x) idiom
> 
> Larry Hastings wrote:
> > Fredrik Lundh wrote:
> >> skip at pobox.com wrote:
> >>   
> >>> MAL's pybench would probably be better for this presuming it does 
> >>> some addition with string operands.
> >>>     
> >> or stringbench.
> >>   
> > 
> > I ran 'em, and they are strangely consistent with pystone.
> > 
> > With concat, stringbench is ever-so-slightly faster 
> overall.  "172.82" 
> > vs "174.85" for the "ascii" column, I guess that's in seconds.  I'm 
> > just happy it's not slower.  (I only ran stringbench once; 
> it seems to 
> > take *forever*).
> > 
> > I ran pybench three times for each build.  The slowest 
> concat overall 
> > time was still 2.9% faster than the fastest release time.
> > "ConcatStrings" is a big winner, at around 150% faster; 
> since the test 
> > doesn't *do* anything with the concatenated values, it 
> never renders 
> > the concatenation objects, so it does a lot less work.
> > "CreateStringsWithConcat" is generally 18-19% faster, as expected.  
> > After that, the timings are all over the place, but some tests were 
> > consistently faster: "CompareInternedStrings" was 8-12% faster, 
> > "DictWithFloatKeys" was 9-11% faster, "SmallLists" was 
> 8-15% faster, 
> > "CompareLongs" was 6-10% faster, and "PyMethodCalls" was 
> 4-6% faster.
> > (These are all comparing the "average run-time" results, though the 
> > "minimum run-time" results were similar.)
> 
> When comparing results, please look at the minimum runtime.
> The average times are just given to indicate how much the 
> mintime differs from the average of all runs.
> 
> > I still couldn't tell you why my results are faster.  I swear on my 
> > mother's eyes I didn't touch anything major involved in 
> > "DictWithFloatKeys", "SmallLists", or "CompareLongs".  I 
> didn't touch 
> > the compiler settings, so that shouldn't be it.  I acknowledge not 
> > only that it could all be a mistake, and that I don't know enough 
> > about it to speculate.//
> 
> Depending on what you changed, it is possible that the layout 
> of the code in memory better fits your CPU architecture.
> 
> If however the speedups are not consistent across several 
> runs of pybench, then it's likely that you have some 
> background activity going on on the machine which causes a 
> slowdown in the unmodified run you chose as basis for the comparison.
> 
> Just to make sure: you are using pybench 2.0, right ?
> 
> --
> Marc-Andre Lemburg
> eGenix.com
> 
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> Oct 09 2006)
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