Review Request 111643: RFC: Use QHash for TypeSystem registry
Commit Hook
null at kde.org
Thu Jul 25 19:30:54 UTC 2013
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http://git.reviewboard.kde.org/r/111643/#review36504
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This review has been submitted with commit 63328cb332c1c647b42ca2efd6fe5214f77a7402 by Milian Wolff to branch master.
- Commit Hook
On July 22, 2013, 6:41 p.m., Milian Wolff wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/111643/
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>
> (Updated July 22, 2013, 6:41 p.m.)
>
>
> Review request for KDevelop.
>
>
> Description
> -------
>
> Use a QHash instead of a fixed-size QVector for the type system registry.
>
> While this is of course slower, the impact is imo negleglible. The benchmark
> shows that the TypeSystem becomes ~20% slower, but that is still nothing in
> total compared to other parts of KDevelop which are actually much slower.
> Thus, limiting the API in such a drastic way (only up to N types) is imo
> not worth it. Instead we can take the small performance impact and improve
> the performance elsewhere :)
>
> Also note that to encounter a slowdown of ~1s one would need to call the TypeSystem
> functions approx. 45 million times. Setting a counter breakpoint on TypeSystem::create
> shows that it's being called less than one million times when loading my biggest KDevelop
> session. So yeah, I think we can safely ignore this time impact and classify the existing
> code as a premature optimization.
>
>
> Diffs
> -----
>
> language/duchain/types/typeregister.h 4843eec
> language/duchain/types/typeregister.cpp 90ed05f
>
> Diff: http://git.reviewboard.kde.org/r/111643/diff/
>
>
> Testing
> -------
>
> Before this patch:
>
> PASS : TestDUChain::initTestCase()
> RESULT : TestDUChain::benchTypeRegistry():"dataClassSize":
> 0.0000299 msecs per iteration (total: 299, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"dynamicSize":
> 0.0000438 msecs per iteration (total: 438, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"create":
> 0.0001276 msecs per iteration (total: 1,276, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"isFactoryLoaded":
> 0.0000271 msecs per iteration (total: 271, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"copy":
> 0.0001812 msecs per iteration (total: 1,812, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"copyNonDynamic":
> 0.0000409 msecs per iteration (total: 409, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"callDestructor":
> 0.0000306 msecs per iteration (total: 306, iterations: 10000000)
> PASS : TestDUChain::benchTypeRegistry()
> PASS : TestDUChain::cleanupTestCase()
> Totals: 3 passed, 0 failed, 0 skipped
> ********* Finished testing of TestDUChain *********
>
> Performance counter stats for './duchaintest benchTypeRegistry -iterations 10000000':
>
> 10077.560833 task-clock # 0.995 CPUs utilized
> 214 context-switches # 0.021 K/sec
> 36 cpu-migrations # 0.004 K/sec
> 171,631 page-faults # 0.017 M/sec
> 11,717,686,879 cycles # 1.163 GHz [83.35%]
> 3,725,598,695 stalled-cycles-frontend # 31.79% frontend cycles idle [83.32%]
> 1,212,888,069 stalled-cycles-backend # 10.35% backend cycles idle [66.74%]
> 19,470,323,749 instructions # 1.66 insns per cycle
> # 0.19 stalled cycles per insn [83.36%]
> 5,693,920,745 branches # 565.010 M/sec [83.33%]
> 1,995,259 branch-misses # 0.04% of all branches [83.27%]
>
> 10.124920649 seconds time elapsed
>
> After this patch:
>
> PASS : TestDUChain::initTestCase()
> RESULT : TestDUChain::benchTypeRegistry():"dataClassSize":
> 0.0000310 msecs per iteration (total: 310, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"dynamicSize":
> 0.0000574 msecs per iteration (total: 574, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"create":
> 0.0001497 msecs per iteration (total: 1,497, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"isFactoryLoaded":
> 0.0000349 msecs per iteration (total: 349, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"copy":
> 0.0001863 msecs per iteration (total: 1,863, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"copyNonDynamic":
> 0.0000522 msecs per iteration (total: 522, iterations: 10000000)
> RESULT : TestDUChain::benchTypeRegistry():"callDestructor":
> 0.0000480 msecs per iteration (total: 480, iterations: 10000000)
> PASS : TestDUChain::benchTypeRegistry()
> PASS : TestDUChain::cleanupTestCase()
> Totals: 3 passed, 0 failed, 0 skipped
> ********* Finished testing of TestDUChain *********
>
> Performance counter stats for './duchaintest benchTypeRegistry -iterations 10000000':
>
> 11514.425401 task-clock # 0.992 CPUs utilized
> 463 context-switches # 0.040 K/sec
> 65 cpu-migrations # 0.006 K/sec
> 171,639 page-faults # 0.015 M/sec
> 14,606,973,287 cycles # 1.269 GHz [83.36%]
> 5,286,680,376 stalled-cycles-frontend # 36.19% frontend cycles idle [83.24%]
> 2,277,868,635 stalled-cycles-backend # 15.59% backend cycles idle [66.67%]
> 21,485,714,055 instructions # 1.47 insns per cycle
> # 0.25 stalled cycles per insn [83.29%]
> 6,111,305,415 branches # 530.752 M/sec [83.38%]
> 2,157,996 branch-misses # 0.04% of all branches [83.35%]
>
> 11.609370777 seconds time elapsed
>
>
> Thanks,
>
> Milian Wolff
>
>
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