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cmd/compile: SSA backend regression causing 6-7% runtime performance loss on crypto/sha3 #14745

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karalabe opened this issue Mar 10, 2016 · 1 comment
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cmd/compile: SSA backend regression causing 6-7% runtime performance loss on crypto/sha3 #14745

karalabe opened this issue Mar 10, 2016 · 1 comment
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@karalabe
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Discussing a possible assembly optimization on the SHA3 crypto package (https://go-review.googlesource.com/#/c/17962/), we've postponed a decision until the SSA branch is merged into develop to see the performance benefit of it.

Today I ran the crypto/sha3 benchmarks against Go 1.6 and Go tip to see how the SSA influences performance, and to my surprise it actually worsened runtime by 6-7%.

  • Old = Go 1.6
  • New = Go tip devel +dbe54d2 Thu Mar 10 07:01:34 2016 +0000 linux/amd64
benchmark                          old ns/op     new ns/op     delta
BenchmarkPermutationFunction-8     515           552           +7.18%
BenchmarkSha3_512_MTU-8            10635         11345         +6.68%
BenchmarkSha3_384_MTU-8            7866          8157          +3.70%
BenchmarkSha3_256_MTU-8            6084          6505          +6.92%
BenchmarkSha3_224_MTU-8            5803          6192          +6.70%
BenchmarkShake128_MTU-8            4878          5453          +11.79%
BenchmarkShake256_MTU-8            5298          5662          +6.87%
BenchmarkShake256_16x-8            76697         81353         +6.07%
BenchmarkShake256_1MiB-8           4057667       4343473       +7.04%
BenchmarkSha3_512_1MiB-8           7543614       8088382       +7.22%

benchmark                          old MB/s     new MB/s     speedup
BenchmarkPermutationFunction-8     388.34       361.78       0.93x
BenchmarkSha3_512_MTU-8            126.93       118.99       0.94x
BenchmarkSha3_384_MTU-8            171.60       165.49       0.96x
BenchmarkSha3_256_MTU-8            221.87       207.53       0.94x
BenchmarkSha3_224_MTU-8            232.61       218.02       0.94x
BenchmarkShake128_MTU-8            276.74       247.54       0.89x
BenchmarkShake256_MTU-8            254.81       238.41       0.94x
BenchmarkShake256_16x-8            213.62       201.39       0.94x
BenchmarkShake256_1MiB-8           258.42       241.41       0.93x
BenchmarkSha3_512_1MiB-8           139.00       129.64       0.93x

Given that everyone was expecting at least some increase in performance, these results are very surprising and imho can be cataloged as a serious regression.
@minux minux changed the title compiler/ssa: regression causing 6-7% runtime performance loss on crypto/sha3 cmd/compile: SSA backend regression causing 6-7% runtime performance loss on crypto/sha3 Mar 10, 2016
@minux minux added this to the Go1.7 milestone Mar 10, 2016
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CL https://golang.org/cl/20488 mentions this issue.

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