69201 – All of JSC's heuristics should be in one place for easier tuning

RESOLVED FIXED Bug 69201

All of JSC's heuristics should be in one place for easier tuning

https://bugs.webkit.org/show_bug.cgi?id=69201

Summary All of JSC's heuristics should be in one place for easier tuning

Filip Pizlo

Reported 2011-09-30 18:17:58 PDT

Currenty JavaScriptCore has a large number of heuristic settings, such as optimization thresholds, recompilation thresholds, optimization delay thresholds, etc. There are also a lot of old heuristics from even before tiered compilation, such as the maximum size of polymorphic access lists and the thrash thresholds for creating dictionaries and despecifying functions. It would be great to have these thresholds in one file (or at least a handful of files), so that it is easier to reason about their relationships. Settings that do not have to be in a header (because they are not accessed frequently and because they don't determine the layout of classes) should be in a .cpp file, so that they can be changed without recompiling all of WebKit. Other settings should be in the corresponding header (of the same name), to make it easier to find them.

Attachments
the patch (25.88 KB, patch) 2011-09-30 21:09 PDT, Filip Pizlo	no flags	Details Formatted Diff Diff
the patch (25.88 KB, patch) 2011-09-30 21:15 PDT, Filip Pizlo	no flags	Details Formatted Diff Diff
the patch - attempt to fix windows (25.90 KB, patch) 2011-09-30 23:11 PDT, Filip Pizlo	oliver: review+	Details Formatted Diff Diff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.

Filip Pizlo

Comment 1 2011-09-30 20:52:12 PDT

I hacked up a patch that does this, and also has an option where all of the heuristics can be controlled using environment variables. This allowed me to tweak around with the various settings. Here's what I find when I increase the threshold for when optimization kicks in by a factor of 10. V8 wins, Kraken loses. This is really worth investigating further. Maybe there's a sweet spot! Benchmark report for SunSpider, V8, and Kraken. VMs tested: "TipOfTree" at /Volumes/Data/pizlo/quinary/OpenSource/WebKitBuild/Release/jsc "Heuristics" at /Volumes/Data/pizlo/senary/OpenSource/WebKitBuild/Release/jsc Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Used 1 benchmark iteration per VM invocation for warm-up. Used the jsc-specific preciseTime() function to get microsecond-level timing. Reporting benchmark execution times with 95% confidence intervals in milliseconds. TipOfTree Heuristics SunSpider: 3d-cube 7.6906+-0.2068 ? 7.7596+-0.2620 ? 3d-morph 7.4465+-0.1283 ? 7.6581+-0.1881 ? might be 1.0284x slower 3d-raytrace 8.2471+-0.1919 ! 8.8701+-0.2425 ! definitely 1.0755x slower access-binary-trees 1.8606+-0.1037 ? 1.9590+-0.0674 ? might be 1.0529x slower access-fannkuch 6.6788+-0.2146 6.5927+-0.2252 might be 1.0131x faster access-nbody 3.6278+-0.1156 ? 3.6838+-0.0670 ? might be 1.0154x slower access-nsieve 2.6637+-0.0730 ? 2.6795+-0.0705 ? bitops-3bit-bits-in-byte 1.7849+-0.0586 1.7360+-0.0279 might be 1.0282x faster bitops-bits-in-byte 2.7555+-0.0986 ! 2.9485+-0.0850 ! definitely 1.0700x slower bitops-bitwise-and 3.3116+-0.1161 3.3052+-0.0942 bitops-nsieve-bits 5.6408+-0.2029 5.6077+-0.1539 controlflow-recursive 2.0679+-0.0469 ? 2.1149+-0.0707 ? might be 1.0227x slower crypto-aes 6.8625+-0.1968 ? 6.9410+-0.4183 ? might be 1.0114x slower crypto-md5 2.8206+-0.0594 ? 2.9170+-0.1876 ? might be 1.0342x slower crypto-sha1 2.5579+-0.0761 ? 2.5948+-0.0808 ? might be 1.0144x slower date-format-tofte 10.1196+-0.3292 10.0692+-0.2650 date-format-xparb 9.6261+-0.2888 9.2702+-0.2785 might be 1.0384x faster math-cordic 6.4324+-0.1322 ? 6.5345+-0.2709 ? might be 1.0159x slower math-partial-sums 7.5616+-0.1605 ? 7.7972+-0.1407 ? might be 1.0312x slower math-spectral-norm 2.8596+-0.1089 ? 2.9433+-0.0722 ? might be 1.0293x slower regexp-dna 10.8983+-0.1859 ? 11.0576+-0.1395 ? might be 1.0146x slower string-base64 6.2564+-0.1731 ^ 5.8365+-0.1670 ^ definitely 1.0719x faster string-fasta 7.1414+-0.1872 7.1134+-0.2382 string-tagcloud 12.0129+-0.3267 ? 12.2721+-0.3626 ? might be 1.0216x slower string-unpack-code 21.6528+-0.6228 20.6743+-0.6671 might be 1.0473x faster string-validate-input 6.6130+-0.2425 ? 6.6702+-0.2608 ? <arithmetic> 6.4304+-0.0354 ? 6.4464+-0.0526 ? <geometric> 5.2719+-0.0380 ? 5.3201+-0.0479 ? <harmonic> 4.3149+-0.0548 ? 4.3748+-0.0496 ? might be 1.0139x slower TipOfTree Heuristics V8: crypto 73.9378+-1.7200 ^ 70.7935+-1.1125 ^ definitely 1.0444x faster deltablue 230.0161+-2.7634 226.3826+-1.2727 might be 1.0161x faster earley-boyer 90.7387+-0.6798 ? 91.2552+-1.1652 ? raytrace 62.5021+-0.8299 62.0781+-0.8338 regexp 106.5030+-1.7636 104.6961+-0.8644 might be 1.0173x faster richards 188.3154+-3.3034 184.6544+-2.0805 might be 1.0198x faster splay 92.9402+-1.3416 91.8982+-0.4769 might be 1.0113x faster <arithmetic> 120.7076+-0.6592 ^ 118.8226+-0.6105 ^ definitely 1.0159x faster <geometric> 108.7153+-0.5950 ^ 107.0578+-0.6092 ^ definitely 1.0155x faster <harmonic> 99.4516+-0.5867 ^ 97.9377+-0.6318 ^ definitely 1.0155x faster TipOfTree Heuristics Kraken: ai-astar 502.3658+-6.5577 ^ 490.1612+-2.0308 ^ definitely 1.0249x faster audio-beat-detection 194.3967+-3.6043 191.6740+-1.0048 might be 1.0142x faster audio-dft 291.1872+-7.7290 286.4926+-5.5645 might be 1.0164x faster audio-fft 129.9101+-2.1400 ^ 126.8271+-0.5652 ^ definitely 1.0243x faster audio-oscillator 269.2837+-3.6560 262.5009+-4.4634 might be 1.0258x faster imaging-darkroom 426.1247+-4.0255 ^ 336.4879+-5.2957 ^ definitely 1.2664x faster imaging-desaturate 229.4139+-2.4708 ? 233.5722+-3.9622 ? might be 1.0181x slower imaging-gaussian-blur 582.8458+-3.2455 ? 591.1324+-9.3164 ? might be 1.0142x slower json-parse-financial 49.6399+-0.6668 49.4632+-0.8152 json-stringify-tinderbox 71.6597+-1.1835 69.6183+-0.9957 might be 1.0293x faster stanford-crypto-aes 132.8525+-1.3210 ^ 102.1307+-1.1175 ^ definitely 1.3008x faster stanford-crypto-ccm 103.1368+-1.0499 101.8944+-0.7486 might be 1.0122x faster stanford-crypto-pbkdf2 195.4435+-4.3892 ! 391.9521+-5.5801 ! definitely 2.0054x slower stanford-crypto-sha256-iterative 85.7275+-0.7357 ? 88.3767+-3.3986 ? might be 1.0309x slower <arithmetic> 233.1420+-0.4635 ! 237.3060+-0.9258 ! definitely 1.0179x slower <geometric> 182.6890+-0.4309 ! 184.1216+-0.3057 ! definitely 1.0078x slower <harmonic> 142.0580+-0.3506 ^ 140.6889+-0.3872 ^ definitely 1.0097x faster TipOfTree Heuristics All benchmarks: <arithmetic> 90.9815+-0.1490 ! 91.9500+-0.2205 ! definitely 1.0106x slower <geometric> 23.7879+-0.1042 ? 23.9089+-0.1269 ? <harmonic> 7.5872+-0.0941 ? 7.6871+-0.0850 ? might be 1.0132x slower

Filip Pizlo

Comment 2 2011-09-30 21:09:22 PDT

Created attachment 109394 [details] the patch This is performance-neutral, as I haven't changed any heuristics in this patch. I have used it to see that there is room to tweak the heuristics, but I don't know yet what the sweet spot is. I'll leave that for another patch.

WebKit Review Bot

Comment 3 2011-09-30 21:11:58 PDT

Attachment 109394 [details] did not pass style-queue: Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/JavaScriptCore/CMakeLists.txt', u'S..." exit_code: 1 Source/JavaScriptCore/runtime/Heuristics.cpp:27: You should add a blank line after implementation file's own header. [build/include_order] [4] Source/JavaScriptCore/runtime/Heuristics.cpp:30: Alphabetical sorting problem. [build/include_order] [4] Total errors found: 2 in 13 files If any of these errors are false positives, please file a bug against check-webkit-style.

Filip Pizlo

Comment 4 2011-09-30 21:15:01 PDT

Created attachment 109395 [details] the patch

Filip Pizlo

Comment 5 2011-09-30 23:11:41 PDT

Created attachment 109398 [details] the patch - attempt to fix windows

Filip Pizlo

Comment 6 2011-10-01 15:04:57 PDT

Landed in r96463.

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Status RESOLVED

Resolution FIXED

Priority P2

Severity Normal

Classification Unclassified

Version 528+ (Nightly build)

Hardware All

OS All

Product WebKit

Component JavaScriptCore

Assignee

Nobody

Reported

2011-09-30 18:17 PDT

Modified

2011-10-01 15:04 PDT History

CC List

5 users Show

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Depends on

Blocks

69208

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