JavaScript code often creates multiple strings that contain the same actual text. Poorly written JavaScript is especially prone to this. This enhancement is to coalesce multiple JSStrings that contain the same text into one common string. Given that JSStrings are immutable, this is possible. The easiest path to start doing this is to hash const strings that are in the backing store for arrays and objects.
Created attachment 141035 [details] Patch for Review Willing to consider other names for JSString::m_isHashConstSingleton. This is some what descriptive of a string with the flag set. Another name could be m_dontHashConstString which is descriptive of its purpose of the flag.
Comment on attachment 141035 [details] Patch for Review Attachment 141035 [details] did not pass gtk-ews (gtk): Output: http://queues.webkit.org/results/12652843
Comment on attachment 141035 [details] Patch for Review Attachment 141035 [details] did not pass win-ews (win): Output: http://queues.webkit.org/results/12652841
Comment on attachment 141035 [details] Patch for Review Attachment 141035 [details] did not pass efl-ews (efl): Output: http://queues.webkit.org/results/12652862
Created attachment 141063 [details] Speculative build fix Enclosed call to MarkStackThreadSharedData::resetChildren() inside parallel GC #if.
Committed r116659: <http://trac.webkit.org/changeset/116659>
This seem to be hitting asserts, bug 86203
Rolling out change.
Rolled out r116659: <http://trac.webkit.org/changeset/116659> in r116822 <http://trac.webkit.org/changeset/116822>.
<rdar://problem/11752030>
(In reply to comment #10) > <rdar://problem/11752030> Actually the original is <rdar://problem/11410050>
Created attachment 150197 [details] Patch with fix for string hash ASSERT failures Updated the code for the case where two marking threads are in the process of hash const'ing the same string. Added a tryHashConstLock() to JSString. When a thread fails to get the lock, it gives up hash con sting the string. The winning thread will be able to hash const. This eliminated several ASSERT failure modes when two threads try to hash a string at nearly the same time.
What's the performance cost of doing this on every garbage collection? What's the cost when there are no strings in the heap, and what's the cost when the heap is 100% unique strings? Is is possible to limit how often we do this string unique-ing?
(In reply to comment #13) > What's the performance cost of doing this on every garbage collection? What's the cost when there are no strings in the heap, and what's the cost when the heap is 100% unique strings? > > Is is possible to limit how often we do this string unique-ing? The performance appears to be neutral overall. v8-splay with DRT looks slower, but using JSC shows it's faster. See below. The no string case is an additional value.isString() check that will fail. The current patch has a hash const kill bit so that strings aren't continuously const'ed. This does mean that we can never get to 100% unique, but it reduces the ongoing const'ing cost. We may want to change this in the future to a const count instead of a single bit to further improve uniqueness. We could limit how often by using a new string since last const threshold or by const'ing in a separate thread that has its own timer. Benchmark report for SunSpider, V8, V8Real, Kraken, JSBench, JSRegress, and DSP on msaboff-pro (MacPro5,1). VMs tested: "Base" at /Volumes/Data/src/webkit.baseline/WebKitBuild/Release/DumpRenderTree (r121160) "HashConst" at /Volumes/Data/src/webkit/WebKitBuild/Release/DumpRenderTree (r121160) Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Emitted a call to gc() between sample measurements. 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. Base HashConst SunSpider: 3d-cube 8.6762+-0.6578 ? 8.6762+-0.6311 ? 3d-morph 7.5697+-0.0574 ? 7.5991+-0.0497 ? 3d-raytrace 14.1252+-0.5765 14.0391+-0.6123 access-binary-trees 2.2856+-0.4548 ? 2.2994+-0.4653 ? access-fannkuch 6.7956+-0.1100 6.7222+-0.0411 might be 1.0109x faster access-nbody 4.1792+-0.0387 ? 4.1858+-0.0307 ? access-nsieve 3.2875+-0.0473 3.2794+-0.0554 bitops-3bit-bits-in-byte 1.3716+-0.0110 ? 1.3736+-0.0088 ? bitops-bits-in-byte 5.7174+-0.0531 5.7145+-0.0367 bitops-bitwise-and 2.2786+-0.0278 2.2595+-0.0074 bitops-nsieve-bits 3.2478+-0.0489 3.2254+-0.0389 controlflow-recursive 2.5888+-0.0212 ? 2.6184+-0.0345 ? might be 1.0114x slower crypto-aes 10.0999+-0.7407 10.0631+-0.7233 crypto-md5 3.6877+-0.1098 ? 3.6952+-0.1158 ? crypto-sha1 3.1664+-0.0248 ? 3.1930+-0.0264 ? date-format-tofte 13.9546+-1.3730 13.6739+-1.3103 might be 1.0205x faster date-format-xparb 12.2760+-0.9493 ? 12.5290+-0.9808 ? might be 1.0206x slower math-cordic 4.1717+-0.0217 ? 4.1975+-0.0397 ? math-partial-sums 9.0324+-0.0220 ? 9.0649+-0.0334 ? math-spectral-norm 3.1152+-0.0256 3.0927+-0.0179 regexp-dna 10.5605+-0.3807 10.4890+-0.3909 string-base64 5.7906+-0.6927 ? 5.8786+-0.6728 ? might be 1.0152x slower string-fasta 8.1582+-0.4101 ? 8.1639+-0.3869 ? string-tagcloud 13.9253+-0.3059 ? 14.0120+-0.3686 ? string-unpack-code 23.1382+-0.8883 ? 23.4292+-0.9274 ? might be 1.0126x slower string-validate-input 8.2838+-0.6484 ? 8.4563+-0.7052 ? might be 1.0208x slower <arithmetic> * 7.3648+-0.2383 ? 7.3820+-0.1900 ? might be 1.0023x slower <geometric> 5.8449+-0.1537 ? 5.8539+-0.1233 ? might be 1.0015x slower <harmonic> 4.5904+-0.0998 ? 4.5962+-0.0929 ? might be 1.0013x slower Base HashConst V8: crypto 77.2960+-0.6339 77.2859+-0.7442 deltablue 138.4858+-2.4387 137.4746+-0.8139 earley-boyer 88.4461+-1.3296 ? 88.9693+-1.4255 ? raytrace 61.7561+-2.8397 ? 62.7029+-2.9255 ? might be 1.0153x slower regexp 88.4419+-0.4629 ? 88.7320+-0.3942 ? richards 127.2255+-1.0954 126.9527+-0.6654 splay 105.2859+-10.6871 ? 109.6264+-10.3128 ? might be 1.0412x slower <arithmetic> 98.1339+-1.3156 ? 98.8205+-1.2472 ? might be 1.0070x slower <geometric> * 94.7000+-1.3117 ? 95.4741+-1.1706 ? might be 1.0082x slower <harmonic> 91.3628+-1.3391 ? 92.1949+-1.1579 ? might be 1.0091x slower Base HashConst V8Real: encrypt 0.40804+-0.00034 ? 0.40864+-0.00038 ? decrypt 7.20393+-0.07552 7.15369+-0.01838 deltablue x2 0.68745+-0.00404 ? 0.68968+-0.00394 ? earley 2.15036+-0.01002 2.13805+-0.01112 boyer 13.95076+-0.09289 ? 14.11211+-0.14308 ? might be 1.0116x slower raytrace x2 5.13411+-0.04329 5.04956+-0.04231 might be 1.0167x faster regexp x2 26.85510+-0.21172 26.59170+-0.05988 richards x2 0.34534+-0.00371 ? 0.34651+-0.00489 ? splay x2 0.79769+-0.00748 ! 0.85507+-0.00308 ! definitely 1.0719x slower <arithmetic> 6.52518+-0.03322 6.49125+-0.01718 might be 1.0052x faster <geometric> * 2.19447+-0.00635 ! 2.21014+-0.00636 ! definitely 1.0071x slower <harmonic> 0.94595+-0.00452 ! 0.95828+-0.00546 ! definitely 1.0130x slower Base HashConst Kraken: ai-astar 803.357+-1.288 796.699+-10.284 audio-beat-detection 207.808+-2.674 ? 208.747+-2.841 ? audio-dft 276.963+-1.532 ? 278.441+-1.212 ? audio-fft 127.160+-0.363 126.917+-0.222 audio-oscillator 239.677+-0.294 239.299+-0.400 imaging-darkroom 299.388+-1.299 296.911+-1.565 imaging-desaturate 225.037+-0.617 224.603+-0.426 imaging-gaussian-blur 438.760+-0.404 ? 439.820+-1.571 ? json-parse-financial 67.232+-0.215 ! 69.052+-0.945 ! definitely 1.0271x slower json-stringify-tinderbox 84.603+-0.408 ? 84.641+-0.274 ? stanford-crypto-aes 89.359+-0.954 88.687+-0.559 stanford-crypto-ccm 99.134+-0.334 ! 99.934+-0.428 ! definitely 1.0081x slower stanford-crypto-pbkdf2 198.419+-1.137 ? 199.866+-1.133 ? stanford-crypto-sha256-iterative 96.168+-0.290 95.958+-0.320 <arithmetic> * 232.362+-0.281 232.113+-0.852 might be 1.0011x faster <geometric> 180.849+-0.276 ? 181.141+-0.281 ? might be 1.0016x slower <harmonic> 147.084+-0.246 ! 147.674+-0.215 ! definitely 1.0040x slower Base HashConst JSBench: amazon 18.2500+-0.2874 18.2500+-0.2874 facebook 71.3333+-2.0692 ? 71.8333+-2.1304 ? google 95.4167+-1.3670 ? 96.4167+-1.6359 ? might be 1.0105x slower twitter 52.3333+-0.3128 52.2500+-0.2874 yahoo 22.0833+-0.1834 ? 22.3333+-0.3128 ? might be 1.0113x slower <arithmetic> * 51.8833+-0.5266 ? 52.2167+-0.5153 ? might be 1.0064x slower <geometric> 42.7856+-0.3461 ? 43.0159+-0.3605 ? might be 1.0054x slower <harmonic> 34.7854+-0.2544 ? 34.9502+-0.3244 ? might be 1.0047x slower Base HashConst JSRegress: adapt-to-double-divide 72.6140+-0.0975 ? 72.6762+-0.1291 ? aliased-arguments-getbyval 0.8366+-0.0105 ? 0.8426+-0.0183 ? arity-mismatch-inlining 0.6412+-0.0075 ? 0.6433+-0.0152 ? big-int-mul 8.4775+-0.0666 ? 8.4849+-0.0677 ? boolean-test 3.5251+-0.0725 3.4780+-0.0278 might be 1.0135x faster cast-int-to-double 12.1047+-0.0604 12.0942+-0.0462 cfg-simplify 3.0606+-0.0178 ? 3.1044+-0.0317 ? might be 1.0143x slower cmpeq-obj-to-obj-other 13.6976+-1.2376 ? 13.8000+-1.1877 ? constant-test 6.8605+-0.0168 6.8537+-0.0235 direct-arguments-getbyval 0.7708+-0.0161 ? 0.7748+-0.0116 ? double-pollution-getbyval 8.8611+-0.0588 ? 8.8782+-0.0548 ? double-pollution-putbyoffset 5.1556+-0.8489 4.4103+-0.0805 might be 1.1690x faster external-arguments-getbyval 2.0881+-0.2468 ? 2.1221+-0.2789 ? might be 1.0163x slower external-arguments-putbyval 3.5392+-0.5579 ? 3.5740+-0.5779 ? Float32Array-matrix-mult 12.0812+-0.9324 11.8524+-1.0004 might be 1.0193x faster fold-double-to-int 38.0619+-1.2160 37.5368+-1.3019 might be 1.0140x faster function-dot-apply 2.7338+-0.0318 2.7226+-0.0249 function-test 4.3704+-0.0179 ! 4.4758+-0.0476 ! definitely 1.0241x slower inline-arguments-access 1.0929+-0.0210 ? 1.1041+-0.0194 ? might be 1.0103x slower inline-arguments-local-escape 28.8715+-3.9518 ? 29.1550+-4.0264 ? int-overflow-local 85.6392+-0.1476 ? 85.8113+-0.2798 ? Int16Array-bubble-sort 68.2007+-0.0937 ! 69.0125+-0.1352 ! definitely 1.0119x slower Int16Array-load-int-mul 1.7721+-0.0142 ? 1.7760+-0.0200 ? Int8Array-load 4.4804+-0.0950 ? 4.6011+-0.1646 ? might be 1.0269x slower integer-divide 13.2724+-0.0415 ? 13.3018+-0.0949 ? method-on-number 184.2202+-1.1002 ! 193.3059+-3.5646 ! definitely 1.0493x slower new-array-dead 23.4163+-0.0934 23.3786+-0.0476 new-array-push 18.0233+-2.4322 17.9705+-2.4527 number-test 3.4411+-0.0510 3.4260+-0.0237 object-test 3.7845+-0.0390 ! 3.8687+-0.0326 ! definitely 1.0223x slower poly-stricteq 79.6322+-0.1355 ? 80.1471+-0.8916 ? rare-osr-exit-on-local 178.8125+-0.1769 ? 178.9686+-0.2493 ? simple-activation-demo 40.5452+-0.6801 40.2360+-0.1038 slow-convergence 79.2538+-0.1947 ? 79.2710+-0.2052 ? sparse-conditional 1.0725+-0.0171 ? 1.0910+-0.0162 ? might be 1.0173x slower string-hash 4.2034+-0.0123 ? 4.2177+-0.0368 ? string-test 3.4052+-0.0247 3.4027+-0.0225 tear-off-arguments 2.7744+-0.0228 ? 2.7791+-0.0202 ? to-int32-boolean 23.1648+-0.0178 ? 23.3756+-0.2807 ? undefined-test 3.7333+-0.0302 ? 3.7437+-0.0342 ? <arithmetic> 26.3073+-0.1262 ? 26.5567+-0.1423 ? might be 1.0095x slower <geometric> * 8.5237+-0.0578 ? 8.5365+-0.0699 ? might be 1.0015x slower <harmonic> 3.4470+-0.0209 ? 3.4603+-0.0207 ? might be 1.0039x slower Base HashConst DSP: filtrr-posterize-tint 44.7237+-0.5850 44.6182+-0.5461 filtrr-tint-contrast-sat-bright 70.5503+-1.0706 70.4246+-0.9774 filtrr-tint-sat-adj-contr-mult 91.5707+-0.5243 ? 92.2560+-0.5432 ? filtrr-blur-overlay-sat-contr 231.3993+-9.9191 225.1883+-2.5697 might be 1.0276x faster filtrr-sat-blur-mult-sharpen-contr 282.3200+-6.5660 ? 283.7610+-6.1809 ? filtrr-sepia-bias 31.4936+-0.5809 31.4092+-0.6969 route9-vp8 x5 1092.6734+-8.0539 ? 1103.7610+-11.1229 ? might be 1.0101x slower <arithmetic> 565.0386+-4.4458 ? 569.6784+-5.0556 ? might be 1.0082x slower <geometric> * 282.7366+-1.8769 ? 283.5124+-1.2426 ? might be 1.0027x slower <harmonic> 119.9613+-0.9288 119.7971+-1.1168 might be 1.0014x faster Base HashConst All benchmarks: <arithmetic> 100.4271+-0.4212 ? 100.9739+-0.4847 ? might be 1.0054x slower <geometric> 16.5144+-0.1072 ? 16.5628+-0.0990 ? might be 1.0029x slower <harmonic> 3.6021+-0.0206 ? 3.6293+-0.0144 ? might be 1.0075x slower Base HashConst Geomean of preferred means: <scaled-result> 33.1934+-0.0806 ? 33.3246+-0.0780 ? might be 1.0040x slower Benchmark report for V8 and V8Real on msaboff-pro (MacPro5,1). VMs tested: "Base" at /Volumes/Data/src/webkit.baseline/WebKitBuild/Release/jsc (r121160) "HashConst" at /Volumes/Data/src/webkit/WebKitBuild/Release/jsc (r121160) Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Emitted a call to gc() between sample measurements. 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. Base HashConst V8: splay 83.1748+-1.5902 ^ 75.0682+-0.7650 ^ definitely 1.1080x faster <arithmetic> 83.1748+-1.5902 ^ 75.0682+-0.7650 ^ definitely 1.1080x faster <geometric> * 83.1748+-1.5902 ^ 75.0682+-0.7650 ^ definitely 1.1080x faster <harmonic> 83.1748+-1.5902 ^ 75.0682+-0.7650 ^ definitely 1.1080x faster Base HashConst V8Real: splay x2 0.93576+-0.01412 ^ 0.81143+-0.00869 ^ definitely 1.1532x faster <arithmetic> 0.93576+-0.01412 ^ 0.81143+-0.00869 ^ definitely 1.1532x faster <geometric> * 0.93576+-0.01412 ^ 0.81143+-0.00869 ^ definitely 1.1532x faster <harmonic> 0.93576+-0.01412 ^ 0.81143+-0.00869 ^ definitely 1.1532x faster Base HashConst All benchmarks: <arithmetic> 28.3488+-0.5350 ^ 25.5637+-0.2509 ^ definitely 1.1089x faster <geometric> 4.1758+-0.0602 ^ 3.6696+-0.0192 ^ definitely 1.1380x faster <harmonic> 1.3958+-0.0210 ^ 1.2106+-0.0128 ^ definitely 1.1530x faster Base HashConst Geomean of preferred means: <scaled-result> 27.8960+-0.4164 ^ 24.6779+-0.0960 ^ definitely 1.1304x faster
> splay x2 0.79769+-0.00748 ! 0.85507+-0.00308 ! definitely 1.0719x slower This result seems to say that we've made GC slower. > splay x2 0.93576+-0.01412 ^ 0.81143+-0.00869 ^ definitely 1.1532x faster This result seems to say that we've made GC faster. I'd like more data on this. Please post results from the GC benchmark I sent you.
Comment on attachment 150197 [details] Patch with fix for string hash ASSERT failures View in context: https://bugs.webkit.org/attachment.cgi?id=150197&action=review r- because of the changes suggested below, and because we need data to figure out if this patch slows down GC. > Source/JavaScriptCore/heap/MarkStack.cpp:532 > + do { Should be: unsigned currentFlags = m_flags; unsigned newFlags = currentFlags | s_hashConstLock; if (!WTF::weakCompareAndSwap(&m_flags, currentFlags, newFlags)) return false; WTF::memoryBarrierAfterLock(); return true; (tryLock should only try once; weak memory ordering platforms like ARM require fences for locks.) > Source/JavaScriptCore/heap/MarkStack.cpp:552 > +ALWAYS_INLINE void MarkStack::internalAppend(JSValue* slot) Let's put a comment here explaining that we're specifically excluding all visits except for visits to object and array backing stores. That way, if someone refactors this code, they'll maintain that requirement. > Source/JavaScriptCore/heap/MarkStack.cpp:560 > + if (value.isString()) { Let's cast to JSCell* before doing this test, to avoid testing isCell() twice. Maybe the compiler will optimize that out for us, but let's not rely on that. > Source/JavaScriptCore/heap/MarkStack.cpp:562 > + if ((string->length() > 1) && !string->isRope() && string->tryHashConstLock()) { Let's use a helper function named shouldTryHashConst, which does all our tests for us: - length > 1 - !isRope - !isHashConstSingleton > Source/JavaScriptCore/runtime/JSString.h:179 > + void releaseHashConstLock() { m_flags &= ~s_hashConstLock; } This needs WTF::memoryBarrierBeforeUnlock().
> We could limit how often by using a new string since last const threshold This sounds good to me.
Created attachment 150492 [details] Updated patch with changes suggested by reviewer These changes eliminate any question of performance regression, especially on v8-splay. The GC benchmark was of marginal use as the numbers seem to worsen over time. I compared before and after numbers after 30 seconds from when the benchmark page loaded to show that the patch is very similar to the baseline. Benchmark report for SunSpider, V8, V8Real, Kraken, JSBench, JSRegress, and DSP on msaboff-pro (MacPro5,1). VMs tested: "Base" at /Volumes/Data/src/webkit.baseline/WebKitBuild/Release/DumpRenderTree (r121689) "HashConst" at /Volumes/Data/src/webkit.work/WebKitBuild/Release/DumpRenderTree (r121689) Collected 12 samples per benchmark/VM, with 4 VM invocations per benchmark. Emitted a call to gc() between sample measurements. 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. Base HashConst SunSpider: 3d-cube 8.0544+-0.4843 ? 8.3723+-0.5080 ? might be 1.0395x slower 3d-morph 7.7863+-0.1308 ? 7.7893+-0.1079 ? 3d-raytrace 11.9975+-0.4714 11.9100+-0.5007 access-binary-trees 2.3276+-0.4307 2.3102+-0.4476 access-fannkuch 6.8067+-0.0173 ? 6.8502+-0.0684 ? access-nbody 4.2047+-0.0456 4.2043+-0.0487 access-nsieve 3.3556+-0.0625 3.2679+-0.0484 might be 1.0268x faster bitops-3bit-bits-in-byte 1.3841+-0.0150 ? 1.3927+-0.0187 ? bitops-bits-in-byte 5.8172+-0.0789 5.7890+-0.0753 bitops-bitwise-and 2.2743+-0.0150 2.2694+-0.0208 bitops-nsieve-bits 3.4734+-0.0399 3.4345+-0.0146 might be 1.0113x faster controlflow-recursive 2.5510+-0.0552 2.4986+-0.0183 might be 1.0210x faster crypto-aes 9.3500+-0.5134 9.3166+-0.5694 crypto-md5 3.5942+-0.1247 3.5358+-0.1064 might be 1.0165x faster crypto-sha1 3.0049+-0.0210 ? 3.0059+-0.0359 ? date-format-tofte 13.4962+-0.9437 ? 13.7100+-1.0121 ? might be 1.0158x slower date-format-xparb 11.8243+-0.6616 ? 12.1386+-0.7611 ? might be 1.0266x slower math-cordic 4.5366+-0.1117 4.5309+-0.0218 math-partial-sums 10.0159+-0.0891 ? 10.0468+-0.0861 ? math-spectral-norm 3.0866+-0.0181 ? 3.1119+-0.0697 ? regexp-dna 10.5978+-0.3863 10.5248+-0.3782 string-base64 5.5663+-0.5029 5.4636+-0.4370 might be 1.0188x faster string-fasta 7.9419+-0.2639 7.9352+-0.2706 string-tagcloud 13.7991+-0.2104 ? 13.8195+-0.2604 ? string-unpack-code 23.5503+-0.5986 22.9889+-0.4340 might be 1.0244x faster string-validate-input 8.7396+-0.5395 8.5304+-0.6068 might be 1.0245x faster <arithmetic> * 7.2745+-0.1588 7.2595+-0.1732 might be 1.0021x faster <geometric> 5.8200+-0.1240 5.8038+-0.1309 might be 1.0028x faster <harmonic> 4.6040+-0.0944 4.5845+-0.0965 might be 1.0042x faster Base HashConst V8: crypto 75.3963+-0.4597 75.1714+-0.6040 deltablue 138.4143+-0.5702 ? 139.5984+-1.4878 ? earley-boyer 89.3543+-1.6485 ? 89.5104+-1.3849 ? raytrace 60.1360+-1.7843 ? 62.0452+-2.8892 ? might be 1.0317x slower regexp 88.1610+-0.4656 87.9296+-0.3581 richards 127.5962+-0.6307 ? 128.5957+-2.0536 ? splay 107.2903+-14.2292 104.4436+-13.9688 might be 1.0273x faster <arithmetic> 98.0498+-1.9328 ? 98.1849+-1.5802 ? might be 1.0014x slower <geometric> * 94.3256+-1.6731 ? 94.5058+-1.3205 ? might be 1.0019x slower <harmonic> 90.7006+-1.3669 ? 90.9741+-0.9908 ? might be 1.0030x slower Base HashConst V8Real: encrypt 0.40839+-0.00114 0.40832+-0.00145 decrypt 7.04424+-0.01547 7.04140+-0.00548 deltablue x2 0.66529+-0.00875 0.66333+-0.00769 earley 2.14376+-0.01243 ? 2.15854+-0.01314 ? boyer 13.95471+-0.03918 13.95424+-0.05520 raytrace x2 5.17177+-0.04428 5.13838+-0.04901 regexp x2 26.59154+-0.08747 ? 26.72360+-0.14260 ? richards x2 0.34671+-0.00355 0.34661+-0.00257 splay x2 0.74072+-0.00383 ^ 0.71081+-0.00533 ^ definitely 1.0421x faster <arithmetic> 6.47023+-0.01220 ? 6.48057+-0.02214 ? might be 1.0016x slower <geometric> * 2.15791+-0.00625 ^ 2.14476+-0.00649 ^ definitely 1.0061x faster <harmonic> 0.92915+-0.00427 0.92163+-0.00407 might be 1.0082x faster Base HashConst Kraken: ai-astar 794.943+-11.039 794.457+-11.576 audio-beat-detection 197.114+-1.162 ? 206.202+-11.136 ? might be 1.0461x slower audio-dft 276.644+-0.650 ? 277.280+-2.925 ? audio-fft 119.476+-0.449 119.453+-0.265 audio-oscillator 243.566+-0.434 ? 244.615+-0.621 ? imaging-darkroom 286.999+-1.415 ? 287.954+-2.334 ? imaging-desaturate 226.815+-0.484 226.659+-0.238 imaging-gaussian-blur 437.352+-1.542 ? 437.453+-2.217 ? json-parse-financial 66.794+-0.230 66.649+-0.262 json-stringify-tinderbox 86.361+-0.918 ? 87.221+-2.289 ? stanford-crypto-aes 87.739+-1.164 86.656+-0.328 might be 1.0125x faster stanford-crypto-ccm 90.307+-0.296 ? 90.763+-0.321 ? stanford-crypto-pbkdf2 196.523+-0.834 ? 196.833+-1.849 ? stanford-crypto-sha256-iterative 96.218+-0.810 ? 96.330+-0.289 ? <arithmetic> * 229.061+-0.818 ? 229.895+-1.476 ? might be 1.0036x slower <geometric> 177.581+-0.290 ? 178.262+-0.859 ? might be 1.0038x slower <harmonic> 144.159+-0.259 ? 144.510+-0.554 ? might be 1.0024x slower Base HashConst JSBench: amazon 18.0833+-0.3272 ? 18.4167+-0.3272 ? might be 1.0184x slower facebook 70.2500+-1.2154 ? 70.4167+-1.5435 ? google 96.1667+-0.7082 96.0000+-1.1494 twitter 53.0833+-0.4248 ^ 52.2500+-0.2874 ^ definitely 1.0159x faster yahoo 22.5000+-0.3318 22.1667+-0.2473 might be 1.0150x faster <arithmetic> * 52.0167+-0.3272 51.8500+-0.3759 might be 1.0032x faster <geometric> 42.9280+-0.2570 42.8264+-0.3306 might be 1.0024x faster <harmonic> 34.8989+-0.2832 ? 34.9147+-0.3509 ? might be 1.0005x slower Base HashConst JSRegress: adapt-to-double-divide 73.0448+-0.2528 ? 73.3176+-0.5147 ? aliased-arguments-getbyval 0.8252+-0.0153 0.8226+-0.0089 arity-mismatch-inlining 0.6705+-0.0089 0.6600+-0.0139 might be 1.0159x faster big-int-mul 8.4999+-0.0774 8.4502+-0.0511 boolean-test 3.5269+-0.0315 3.5131+-0.0294 cast-int-to-double 12.0900+-0.0306 ? 12.1129+-0.0621 ? cfg-simplify 3.0696+-0.0116 ? 3.0845+-0.0310 ? cmpeq-obj-to-obj-other 8.6143+-0.3413 8.4200+-0.0558 might be 1.0231x faster constant-test 6.8671+-0.0285 6.8647+-0.0593 direct-arguments-getbyval 0.7700+-0.0082 0.7698+-0.0149 double-pollution-getbyval 9.2234+-0.0308 9.2041+-0.0153 double-pollution-putbyoffset 4.7886+-0.6114 ? 5.1147+-0.8163 ? might be 1.0681x slower external-arguments-getbyval 2.1439+-0.2492 2.1198+-0.2117 might be 1.0114x faster external-arguments-putbyval 3.7456+-0.4770 ? 3.8689+-0.4926 ? might be 1.0329x slower Float32Array-matrix-mult 11.3750+-0.5663 ? 11.7441+-0.6744 ? might be 1.0324x slower fold-double-to-int 38.1196+-0.6664 37.6831+-0.3176 might be 1.0116x faster function-dot-apply 2.6112+-0.0324 ^ 2.5639+-0.0080 ^ definitely 1.0185x faster function-test 4.0352+-0.0778 ? 4.0651+-0.0418 ? inline-arguments-access 1.1399+-0.0121 ? 1.1551+-0.0184 ? might be 1.0134x slower inline-arguments-local-escape 22.8221+-0.3672 ? 23.1902+-0.3512 ? might be 1.0161x slower int-overflow-local 85.7052+-0.2149 85.5160+-0.1651 Int16Array-bubble-sort 66.9235+-1.3807 66.3555+-0.2462 Int16Array-load-int-mul 1.7750+-0.0209 1.7710+-0.0257 Int8Array-load 4.5036+-0.1126 4.4873+-0.0903 integer-divide 12.8903+-0.0449 ? 12.9670+-0.1169 ? method-on-number 189.3689+-1.0929 ? 191.4051+-2.0277 ? might be 1.0108x slower new-array-dead 23.3886+-0.0952 ? 23.4266+-0.1534 ? new-array-push 10.8416+-1.6158 10.8325+-1.6281 number-test 3.4584+-0.0255 3.4408+-0.0363 object-test 3.8524+-0.0439 ? 3.9079+-0.0321 ? might be 1.0144x slower poly-stricteq 79.1842+-0.8449 ? 80.9045+-1.7510 ? might be 1.0217x slower rare-osr-exit-on-local 175.2612+-1.1155 173.8743+-0.6069 simple-activation-demo 40.1248+-0.4975 39.9025+-0.5046 slow-convergence 78.5798+-0.2815 ? 78.8012+-0.2196 ? sparse-conditional 1.0674+-0.0153 1.0600+-0.0132 string-hash 4.2261+-0.0215 ? 4.2363+-0.0447 ? string-test 3.4048+-0.0327 3.3857+-0.0127 tear-off-arguments 2.9834+-0.0114 ? 2.9946+-0.0141 ? to-int32-boolean 23.1747+-0.0693 23.1611+-0.0303 undefined-test 3.7980+-0.0602 3.7848+-0.0540 <arithmetic> 25.8124+-0.0986 ? 25.8735+-0.1072 ? might be 1.0024x slower <geometric> * 8.2821+-0.0552 ? 8.2997+-0.0463 ? might be 1.0021x slower <harmonic> 3.4528+-0.0129 3.4489+-0.0130 might be 1.0011x faster Base HashConst DSP: filtrr-posterize-tint 44.1847+-0.7029 43.9408+-0.6471 filtrr-tint-contrast-sat-bright 70.3021+-0.5723 ? 71.8130+-2.5226 ? might be 1.0215x slower filtrr-tint-sat-adj-contr-mult 90.3652+-0.6997 ? 92.1827+-1.9895 ? might be 1.0201x slower filtrr-blur-overlay-sat-contr 223.4736+-4.6838 ? 224.0483+-4.6761 ? filtrr-sat-blur-mult-sharpen-contr 274.9528+-1.7327 ? 277.0566+-2.0776 ? filtrr-sepia-bias 33.1090+-0.4371 ? 33.1363+-0.5593 ? route9-vp8 x5 1081.0710+-10.5430 1077.9987+-6.9789 starfield x5 1172.4700+-9.5640 ? 1176.9836+-6.9101 ? <arithmetic> 750.2558+-5.9386 ? 751.0681+-3.3128 ? might be 1.0011x slower <geometric> * 438.4555+-2.5311 ? 439.8283+-1.7897 ? might be 1.0031x slower <harmonic> 168.1541+-1.2405 ? 168.9105+-1.9142 ? might be 1.0045x slower Base HashConst All benchmarks: <arithmetic> 143.1933+-0.8390 ? 143.4145+-0.4087 ? might be 1.0015x slower <geometric> 19.3711+-0.1199 ? 19.3760+-0.1130 ? might be 1.0003x slower <harmonic> 3.7289+-0.0144 3.7107+-0.0102 might be 1.0049x faster Base HashConst Geomean of preferred means: <scaled-result> 34.9745+-0.1795 34.9713+-0.1493 might be 1.0001x faster
Comment on attachment 150492 [details] Updated patch with changes suggested by reviewer View in context: https://bugs.webkit.org/attachment.cgi?id=150492&action=review > Source/JavaScriptCore/ChangeLog:68 > - > - * runtime/JSArray.cpp: > + * runtime/JSArray.cpp: ? > Source/JavaScriptCore/runtime/JSString.h:169 > + static JS_EXPORTDATA unsigned s_newStringsSinceLastGC; This isn't thread safe -- we have multiple heaps independtly being GC'd so this needs to be a per-heap field. > Source/JavaScriptCore/runtime/JSString.h:195 > + static const unsigned s_hashConstLock = 1u << 2; > + static const unsigned s_isHashConstSingleton = 1u << 1; > + static const unsigned s_is8Bit = 1u; Would be nicer (and less likely for the compiler to do anything stupid) as: enum { hashConstLock = 1u << 2, isHashConstSingleton = 1u << 1, s_is8Bit = 1u };
Created attachment 150503 [details] Patch with suggested fixes
Comment on attachment 150503 [details] Patch with suggested fixes Attachment 150503 [details] did not pass efl-ews (efl): Output: http://queues.webkit.org/results/13124314
Created attachment 150505 [details] FFixed build issues.
Created attachment 150656 [details] Fixed a minor bug and improved new strings since last hash const logic Fixed that the strings since last Hash Const threshold boolean is in MarkStackThreadSharedData and not MarkStack. Change the clearing of the number of new strings since last GC is only done at the end of a GC where we actually hash const'ed strings.
Committed r121806: <http://trac.webkit.org/changeset/121806>
> The GC benchmark was of marginal use as the numbers seem to worsen over time. I compared before and after numbers after 30 seconds from when the benchmark page loaded to show that the patch is very similar to the baseline. Can you give more detail here? What's the rate of worsening over time? What were the two numbers you measured, which were "very similar"?