fd82718e06
On riscv64 we need 8 byte alignment for 8 byte loads - the existing check was only ensuring 4 byte alignment, which potentially results in unaligned loads being performed. Unaligned loads incur a significant performance penality due to the resulting kernel traps and fix ups. Adjust BenchmarkCompareBytesBigUnaligned so that this issue would have been more readily visible. Updates #50615 name old time/op new time/op delta CompareBytesBigUnaligned/offset=1-4 6.98ms _ 5% 6.84ms _ 3% ~ (p=0.319 n=5+5) CompareBytesBigUnaligned/offset=2-4 6.75ms _ 1% 6.99ms _ 4% ~ (p=0.063 n=5+5) CompareBytesBigUnaligned/offset=3-4 6.84ms _ 1% 6.74ms _ 1% -1.48% (p=0.003 n=5+5) CompareBytesBigUnaligned/offset=4-4 146ms _ 1% 7ms _ 6% -95.08% (p=0.000 n=5+5) CompareBytesBigUnaligned/offset=5-4 7.05ms _ 5% 6.75ms _ 1% ~ (p=0.079 n=5+5) CompareBytesBigUnaligned/offset=6-4 7.11ms _ 5% 6.89ms _ 5% ~ (p=0.177 n=5+5) CompareBytesBigUnaligned/offset=7-4 7.14ms _ 5% 6.91ms _ 6% ~ (p=0.165 n=5+5) name old speed new speed delta CompareBytesBigUnaligned/offset=1-4 150MB/s _ 5% 153MB/s _ 3% ~ (p=0.336 n=5+5) CompareBytesBigUnaligned/offset=2-4 155MB/s _ 1% 150MB/s _ 4% ~ (p=0.058 n=5+5) CompareBytesBigUnaligned/offset=3-4 153MB/s _ 1% 156MB/s _ 1% +1.51% (p=0.004 n=5+5) CompareBytesBigUnaligned/offset=4-4 7.16MB/s _ 1% 145.79MB/s _ 6% +1936.23% (p=0.000 n=5+5) CompareBytesBigUnaligned/offset=5-4 149MB/s _ 5% 155MB/s _ 1% ~ (p=0.078 n=5+5) CompareBytesBigUnaligned/offset=6-4 148MB/s _ 5% 152MB/s _ 5% ~ (p=0.175 n=5+5) CompareBytesBigUnaligned/offset=7-4 147MB/s _ 5% 152MB/s _ 6% ~ (p=0.160 n=5+5) Change-Id: I2c859e061919db482318ce63b85b808aa973a9ba Reviewed-on: https://go-review.googlesource.com/c/go/+/431099 Reviewed-by: Meng Zhuo <mzh@golangcn.org> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Joel Sing <joel@sing.id.au> Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
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