| commit | fe24837c4de6dac36f3496e6bac85f72209ee841 | [log] [tgz] |
|---|---|---|
| author | Josh Bleecher Snyder <josharian@gmail.com> | Sun Mar 03 14:47:20 2019 -0800 |
| committer | Josh Bleecher Snyder <josharian@gmail.com> | Sat Mar 09 20:33:46 2019 +0000 |
| tree | c5062b52de9917f8a3ef77cd52a9e622cb8fa79f | |
| parent | 4c227a091e9200ed9757dedd8efbc6e254750c2c [diff] |
math/big: add fast path for pure Go addVW for large z In the normal case, only a few words have to be updated when adding a word to a vector. When that happens, we can simply copy the rest of the words, which is much faster. However, the overhead of that makes it prohibitive for small vectors, so we check the size at the beginning. The implementation is a bit weird to allow addVW to continued to be inlined; see #30548. The AddVW benchmarks are surprising, but fully repeatable. The SubVW benchmarks are more or less as expected. I expect that removing the indirect function call will help both and make them a bit more normal. name old time/op new time/op delta AddVW/1-8 4.27ns ± 2% 3.81ns ± 3% -10.83% (p=0.000 n=89+90) AddVW/2-8 4.91ns ± 2% 4.34ns ± 1% -11.60% (p=0.000 n=83+90) AddVW/3-8 5.77ns ± 4% 5.76ns ± 2% ~ (p=0.365 n=91+87) AddVW/4-8 6.03ns ± 1% 6.03ns ± 1% ~ (p=0.392 n=80+76) AddVW/5-8 6.48ns ± 2% 6.63ns ± 1% +2.27% (p=0.000 n=76+74) AddVW/10-8 9.56ns ± 2% 9.56ns ± 1% -0.02% (p=0.002 n=69+76) AddVW/100-8 90.6ns ± 0% 18.1ns ± 4% -79.99% (p=0.000 n=72+94) AddVW/1000-8 865ns ± 0% 85ns ± 6% -90.14% (p=0.000 n=66+96) AddVW/10000-8 8.57µs ± 2% 1.82µs ± 3% -78.73% (p=0.000 n=99+94) AddVW/100000-8 84.4µs ± 2% 31.8µs ± 4% -62.29% (p=0.000 n=93+98) name old time/op new time/op delta SubVW/1-8 3.90ns ± 2% 4.13ns ± 4% +6.02% (p=0.000 n=92+95) SubVW/2-8 4.15ns ± 1% 5.20ns ± 1% +25.22% (p=0.000 n=83+85) SubVW/3-8 5.50ns ± 2% 6.22ns ± 6% +13.21% (p=0.000 n=91+97) SubVW/4-8 5.99ns ± 1% 6.63ns ± 1% +10.63% (p=0.000 n=79+61) SubVW/5-8 6.75ns ± 4% 6.88ns ± 2% +1.82% (p=0.000 n=98+73) SubVW/10-8 9.57ns ± 1% 9.56ns ± 1% -0.13% (p=0.000 n=77+64) SubVW/100-8 90.3ns ± 1% 18.1ns ± 2% -80.00% (p=0.000 n=75+94) SubVW/1000-8 860ns ± 4% 85ns ± 7% -90.14% (p=0.000 n=97+99) SubVW/10000-8 8.51µs ± 3% 1.77µs ± 6% -79.21% (p=0.000 n=100+97) SubVW/100000-8 84.4µs ± 3% 31.5µs ± 3% -62.66% (p=0.000 n=92+92) Change-Id: I721d7031d40f245b4a284f5bdd93e7bb85e7e937 Reviewed-on: https://go-review.googlesource.com/c/go/+/164968 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
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