[jsc-dev] [webkit-dev] Proposal: Using LLInt Asm in major architectures even if JIT is disabled
Saam Barati
sbarati at apple.com
Wed Sep 19 23:08:11 PDT 2018
Interesting! I must have not run this experiment correctly when I did it.
- Saam
> On Sep 19, 2018, at 7:31 PM, Yusuke Suzuki <yusukesuzuki at slowstart.org> wrote:
>
>> On Thu, Sep 20, 2018 at 12:54 AM Saam Barati <sbarati at apple.com> wrote:
>> To elaborate: I ran this same experiment before. And I forgot to turn off the RegExp JIT and got results similar to what you got. Once I turned off the RegExp JIT, I saw no perf difference.
>
> Yeah, I disabled JIT and RegExpJIT explicitly by using
>
> export JSC_useJIT=false
> export JSC_useRegExpJIT=false
>
> and I checked no JIT code is generated by running dumpDisassembly. And I also put `CRASH()` in ExecutableAllocator::singleton() to ensure no executable memory is allocated.
> The result is the same. I think `useJIT=false` disables RegExp JIT too.
>
> baseline patched
>
> ai-astar 3499.046+-14.772 ^ 1897.624+-234.517 ^ definitely 1.8439x faster
> audio-beat-detection 1803.466+-491.965 970.636+-428.051 might be 1.8580x faster
> audio-dft 1756.985+-68.710 ^ 954.312+-528.406 ^ definitely 1.8411x faster
> audio-fft 1637.969+-458.129 850.083+-449.228 might be 1.9268x faster
> audio-oscillator 1866.006+-569.581 ^ 967.194+-82.521 ^ definitely 1.9293x faster
> imaging-darkroom 2156.526+-591.042 ^ 1231.318+-187.297 ^ definitely 1.7514x faster
> imaging-desaturate 3059.335+-284.740 ^ 1754.128+-339.941 ^ definitely 1.7441x faster
> imaging-gaussian-blur 16034.828+-1930.938 ^ 7389.919+-2228.020 ^ definitely 2.1698x faster
> json-parse-financial 60.273+-4.143 53.935+-28.957 might be 1.1175x faster
> json-stringify-tinderbox 39.497+-3.915 38.146+-9.652 might be 1.0354x faster
> stanford-crypto-aes 873.623+-208.225 ^ 486.350+-132.379 ^ definitely 1.7963x faster
> stanford-crypto-ccm 538.707+-33.979 ^ 285.944+-41.570 ^ definitely 1.8840x faster
> stanford-crypto-pbkdf2 1929.960+-649.861 ^ 1044.320+-1.182 ^ definitely 1.8481x faster
> stanford-crypto-sha256-iterative 614.344+-200.228 342.574+-123.524 might be 1.7933x faster
>
> <arithmetic> 2562.183+-207.456 ^ 1304.749+-312.963 ^ definitely 1.9637x faster
>
> I think this result is not related to RegExp JIT since ai-astar is not using RegExp.
>
> Best regards,
> Yusuke Suzuki
>
>>
>> - Saam
>>
>>> On Sep 19, 2018, at 8:53 AM, Saam Barati <sbarati at apple.com> wrote:
>>>
>>> Did you turn off the RegExp JIT?
>>>
>>> - Saam
>>>
>>>> On Sep 18, 2018, at 11:23 PM, Yusuke Suzuki <yusukesuzuki at slowstart.org> wrote:
>>>>
>>>> Hi WebKittens!
>>>>
>>>> Recently, node-jsc is announced[1]. When I read the documents of that project,
>>>> I found that they use LLInt ASM interpreter instead of CLoop in non-JIT environment.
>>>> So I had one question in my mind: How fast the LLInt ASM interpreter when comparing to CLoop?
>>>>
>>>> I've set up two builds. One is CLoop build (-DENABLE_JIT=OFF) and another is JIT build JSC with `JSC_useJIT=false`.
>>>> And I've ran kraken benchmarks with these two builds in x64 Linux machine. The results are the followings.
>>>>
>>>> Benchmark report for Kraken on sakura-trick.
>>>>
>>>> VMs tested:
>>>> "baseline" at /home/yusukesuzuki/dev/WebKit/WebKitBuild/nojit/Release/bin/jsc
>>>> "patched" at /home/yusukesuzuki/dev/WebKit/WebKitBuild/nojit-llint/Release/bin/jsc
>>>>
>>>> Collected 10 samples per benchmark/VM, with 10 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.
>>>>
>>>> baseline patched
>>>>
>>>> ai-astar 3619.974+-57.095 ^ 2014.835+-59.016 ^ definitely 1.7967x faster
>>>> audio-beat-detection 1762.085+-24.853 ^ 1030.902+-19.743 ^ definitely 1.7093x faster
>>>> audio-dft 1822.426+-28.704 ^ 909.262+-16.640 ^ definitely 2.0043x faster
>>>> audio-fft 1651.070+-9.994 ^ 865.203+-7.912 ^ definitely 1.9083x faster
>>>> audio-oscillator 1853.697+-26.539 ^ 992.406+-12.811 ^ definitely 1.8679x faster
>>>> imaging-darkroom 2118.737+-23.219 ^ 1303.729+-8.071 ^ definitely 1.6251x faster
>>>> imaging-desaturate 3133.654+-28.545 ^ 1759.738+-18.182 ^ definitely 1.7808x faster
>>>> imaging-gaussian-blur 16321.090+-154.893 ^ 7228.017+-58.508 ^ definitely 2.2580x faster
>>>> json-parse-financial 57.256+-2.876 56.101+-4.265 might be 1.0206x faster
>>>> json-stringify-tinderbox 38.470+-2.788 ? 38.771+-0.935 ?
>>>> stanford-crypto-aes 851.341+-7.738 ^ 485.438+-13.904 ^ definitely 1.7538x faster
>>>> stanford-crypto-ccm 556.133+-6.606 ^ 264.161+-3.970 ^ definitely 2.1053x faster
>>>> stanford-crypto-pbkdf2 1945.718+-15.968 ^ 1075.013+-13.337 ^ definitely 1.8099x faster
>>>> stanford-crypto-sha256-iterative 623.203+-7.604 ^ 349.782+-12.810 ^ definitely 1.7817x faster
>>>>
>>>> <arithmetic> 2596.775+-14.857 ^ 1312.383+-8.840 ^ definitely 1.9787x faster
>>>>
>>>> Surprisingly, LLInt ASM interpreter is significantly faster than CLoop. I expected it would be fast, but it would show around 10% performance win.
>>>> But the reality is that it is 2x faster. It is too much number to me to consider enabling LLInt ASM interpreter for non-JIT build configuration.
>>>> As a bonus, LLInt ASM interpreter offers sampling profiler support even in non-JIT environment.
>>>>
>>>> So my proposal is, how about enabling LLInt ASM interpreter in non-JIT configuration environment in major architectures (x64 and ARM64)?
>>>>
>>>> Best regards,
>>>> Yusuke Suzuki
>>>>
>>>> [1]: https://lists.webkit.org/pipermail/webkit-dev/2018-September/030140.html
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