[Patches] [ python-Patches-479615 ] Fast-path for interned string compares
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Thu, 08 Aug 2002 14:16:25 -0700
Patches item #479615, was opened at 2001-11-08 15:19
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Category: Core (C code)
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: M.-A. Lemburg (lemburg)
Assigned to: M.-A. Lemburg (lemburg)
Summary: Fast-path for interned string compares
Initial Comment:
This patch adds a fast-path for comparing equality of interned strings.
The patch boosts performance for comparing identical string objects
by some 20% on my machine while not causing any noticable slow-down
for other operations (according to tests done with pybench).
More infos and benchmarks later...
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>Comment By: M.-A. Lemburg (lemburg)
Date: 2002-08-08 21:16
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I still consider the patch worth adding. The application space
where it helps may be small, but also important: it can
massively
speed up parsers which use interned strings as tokens.
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Comment By: Martin v. Löwis (loewis)
Date: 2002-08-08 21:07
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Is there any progress on this patch, or should it be
considered withdrawn?
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Comment By: Neil Schemenauer (nascheme)
Date: 2002-03-23 23:35
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Attached is an updated version of this patch. I'm -0 on it
since it doesn't seem to help much except for artificial
benchmarks.
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Comment By: M.-A. Lemburg (lemburg)
Date: 2001-11-08 15:26
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Output from pybench comparing today's CVS Python with patch (eqpython) and without patch (stdpython):
PYBENCH 1.0
Benchmark: eqpython.bench (rounds=10, warp=20)
Tests: per run per oper. diff *)
------------------------------------------------------------------------
BuiltinFunctionCalls: 125.55 ms 0.98 us -1.68%
BuiltinMethodLookup: 180.10 ms 0.34 us +1.75%
CompareFloats: 107.30 ms 0.24 us +2.04%
CompareFloatsIntegers: 185.15 ms 0.41 us -0.05%
CompareIntegers: 163.50 ms 0.18 us -1.77%
CompareInternedStrings: 79.50 ms 0.16 us -20.78%
^^^^^^^^^^^^^^^^^^^^ This is the interesting line :-) ^^^^^^^^^^^^^^^^^^^^^^^^^^
CompareLongs: 110.25 ms 0.24 us +0.09%
CompareStrings: 143.40 ms 0.29 us +2.14%
CompareUnicode: 118.00 ms 0.31 us +1.68%
ConcatStrings: 189.55 ms 1.26 us -1.61%
ConcatUnicode: 226.55 ms 1.51 us +1.34%
CreateInstances: 202.35 ms 4.82 us -1.87%
CreateStringsWithConcat: 221.00 ms 1.11 us +0.45%
CreateUnicodeWithConcat: 240.00 ms 1.20 us +1.27%
DictCreation: 213.25 ms 1.42 us +0.47%
DictWithFloatKeys: 263.50 ms 0.44 us +1.15%
DictWithIntegerKeys: 158.50 ms 0.26 us -1.86%
DictWithStringKeys: 147.60 ms 0.25 us +0.75%
ForLoops: 144.90 ms 14.49 us -4.64%
IfThenElse: 174.15 ms 0.26 us -0.00%
ListSlicing: 88.80 ms 25.37 us -1.11%
NestedForLoops: 136.95 ms 0.39 us +3.01%
NormalClassAttribute: 177.80 ms 0.30 us -2.68%
NormalInstanceAttribute: 166.85 ms 0.28 us -0.54%
PythonFunctionCalls: 152.20 ms 0.92 us +1.40%
PythonMethodCalls: 133.70 ms 1.78 us +1.60%
Recursion: 119.45 ms 9.56 us +0.04%
SecondImport: 124.65 ms 4.99 us -6.03%
SecondPackageImport: 130.70 ms 5.23 us -5.73%
SecondSubmoduleImport: 161.65 ms 6.47 us -5.88%
SimpleComplexArithmetic: 245.50 ms 1.12 us +2.08%
SimpleDictManipulation: 108.50 ms 0.36 us +0.05%
SimpleFloatArithmetic: 125.80 ms 0.23 us +0.84%
SimpleIntFloatArithmetic: 128.50 ms 0.19 us -1.46%
SimpleIntegerArithmetic: 128.45 ms 0.19 us -0.77%
SimpleListManipulation: 159.15 ms 0.59 us -5.32%
SimpleLongArithmetic: 189.55 ms 1.15 us +2.65%
SmallLists: 293.70 ms 1.15 us -5.26%
SmallTuples: 230.00 ms 0.96 us +0.44%
SpecialClassAttribute: 175.70 ms 0.29 us -2.79%
SpecialInstanceAttribute: 199.70 ms 0.33 us -1.55%
StringMappings: 196.85 ms 1.56 us -2.48%
StringPredicates: 133.00 ms 0.48 us -8.28%
StringSlicing: 165.45 ms 0.95 us -3.47%
TryExcept: 193.60 ms 0.13 us +0.57%
TryRaiseExcept: 175.40 ms 11.69 us +0.69%
TupleSlicing: 156.85 ms 1.49 us -0.00%
UnicodeMappings: 175.90 ms 9.77 us +1.76%
UnicodePredicates: 141.35 ms 0.63 us +0.78%
UnicodeProperties: 184.35 ms 0.92 us -2.10%
UnicodeSlicing: 179.45 ms 1.03 us -1.10%
------------------------------------------------------------------------
Average round time: 9855.00 ms -1.13%
*) measured against: stdpython.bench (rounds=10, warp=20)
As you can see, the rest of the results don't change much and the
ones that do indicate some additional benefit gained by the patch.
All slow-downs are way below the noise limit of around 5-10% (depending
the platforms/machine/compiler).
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