Very sorry Stephen, that is crazy bad. We'll get on this immediately and get it 
understood and fixed asap.

paul


> On Nov 3, 2014, at 2:59 PM, Stephen <[email protected]> wrote:
> 
> Dear v8-users,
> 
> We have a port of Chromium to a MIPS(el) embedded system, and are currently 
> in the process of upgrading it from M31 (31.0.1650.61, v8 version 
> 3.21.18.9[1]) to M37 (37.0.2062.0, v8 version 3.27.34.0[1]). In doing so, we 
> have run into what seems to be a serious regression in V8 performance. 
> Running the Octane benchmark 
> (http://octane-benchmark.googlecode.com/svn/latest/index.html), these are the 
> numbers on our platform for M31 and M37:
> 
> M31:
> 
> Richards: 1578
> DeltaBlue: 951
> Crypto: 1133
> RayTrace: 1830
> EarleyBoyer: 2347
> RegExp: 256
> Splay: 341
> SplayLatency: 1434
> NavierStokes: 1223
> PdfJS: 580
> Mandreel: 654
> MandreelLatency: 649
> Gameboy: 1112
> CodeLoad: 756
> Box2D: 501
> zlib: 1769
> Typescript: 887
> Overall: 905
> 
> M37:
> 
> Richards: 5.88
> DeltaBlue: 3.66
> Crypto: 21.4
> RayTrace: 15.3
> EarleyBoyer: 67.4
> RegExp: 57.9
> Splay: 55.5
> SplayLatency: 487
> NavierStokes: 36.6
> PdfJS: 50.2
> Mandreel: 4.60
> MandreelLatency: 66.2
> Gameboy: 1589
> CodeLoad: 801
> Box2D: 689
> zlib: 2650
> Typescript: 968
> Overall: 87.0
> 
> Obviously we are rather concerned by these numbers - a 10x degradation in 
> overall score, and nearly 300x in some benchmarks! SunSpider shows similar 
> levels of regression - a 3x overall increase in time taken, and multiple 
> 100x's in some individual benchmarks.
> 
> I have begun to dig into some of the benchmarks, and am attaching traces 
> taken against the Octane 'crypto' benchmark on M31 and M37 using the 
> --js-flags="--perf" switch. The M37 version seems to spend an enormous amount 
> of time in the 'am3' function: 16913 ticks (as opposed to 39 ticks in the M31 
> case). Might this indicate some sort of regression in MIPS math code?
> 
> Are there any known performance regressions in v8 on MIPS(el) in M37, or any 
> suggestions on how we can debug this further? Feel free to ask for further 
> information/testing/etc, and I will do my best to provide! I have tried to 
> build standalone ToT V8 for our platform, but ran into issues with warnings 
> being converted to errors that I haven't dealt with yet.
> 
> Thanks,
> Stephen
> 
> [1]: According to http://omahaproxy.appspot.com/
> 
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> <v8_m37_crypto_trace.log><v8_m31_crypto_trace.log>

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