diff options
author | Joel Sing <joel@sing.id.au> | 2022-09-17 16:55:57 +1000 |
---|---|---|
committer | Joel Sing <joel@sing.id.au> | 2022-09-19 18:59:50 +0000 |
commit | fd82718e06a7b8a32becb1751592854d49904075 (patch) | |
tree | bae05ec1b21f4ea2febeaa9f220ac1acc317a419 /src/bytes | |
parent | ceffdc8545c3155b030de9e91d399dc34bd3c678 (diff) | |
download | go-fd82718e06a7b8a32becb1751592854d49904075.tar.gz go-fd82718e06a7b8a32becb1751592854d49904075.zip |
internal/bytealg: correct alignment checks for compare/memequal on riscv64
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>
Diffstat (limited to 'src/bytes')
-rw-r--r-- | src/bytes/compare_test.go | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/src/bytes/compare_test.go b/src/bytes/compare_test.go index a595d575d0..a0150abd99 100644 --- a/src/bytes/compare_test.go +++ b/src/bytes/compare_test.go @@ -6,6 +6,7 @@ package bytes_test import ( . "bytes" + "fmt" "internal/testenv" "testing" ) @@ -213,22 +214,30 @@ func BenchmarkCompareBytesDifferentLength(b *testing.B) { } } -func BenchmarkCompareBytesBigUnaligned(b *testing.B) { +func benchmarkCompareBytesBigUnaligned(b *testing.B, offset int) { b.StopTimer() b1 := make([]byte, 0, 1<<20) for len(b1) < 1<<20 { b1 = append(b1, "Hello Gophers!"...) } - b2 := append([]byte("hello"), b1...) + b2 := append([]byte("12345678")[:offset], b1...) b.StartTimer() - for i := 0; i < b.N; i++ { - if Compare(b1, b2[len("hello"):]) != 0 { + for j := 0; j < b.N; j++ { + if Compare(b1, b2[offset:]) != 0 { b.Fatal("b1 != b2") } } b.SetBytes(int64(len(b1))) } +func BenchmarkCompareBytesBigUnaligned(b *testing.B) { + for i := 1; i < 8; i++ { + b.Run(fmt.Sprintf("offset=%d", i), func(b *testing.B) { + benchmarkCompareBytesBigUnaligned(b, i) + }) + } +} + func BenchmarkCompareBytesBig(b *testing.B) { b.StopTimer() b1 := make([]byte, 0, 1<<20) |