pingcap/tidb
Voir sur GitHubuse monotonic time directly instead of Go time in somewhere
Open
#32 121 ouverte le 7 févr. 2022
help wantedtype/enhancementtype/performance
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- (Merge moyen 14j 4h) (346 PRs mergées en 30 j)
Description
Enhancement
In TiDB, we heavily use Go time.Now to calculate the duration of some operations, e.g. prometheus Histogram, query time, etc.
For time.Now, this function will call walltime and nanotime, but in the above scenario, we only need to call nanotime(monotonic clock) to calculate the duration.
import _ "unsafe"
//go:noescape
//go:linkname nanotime runtime.nanotime
func nanotime() int64
func Now() time.Duration {
return time.Duration(nanotime())
}
Here is a simple implementation for Nanotime,
func BenchmarkTime1(b *testing.B) {
for i := 0; i < b.N; i++ {
time.Now()
}
}
func BenchmarkTime2(b *testing.B) {
for i := 0; i < b.N; i++ {
Now()
}
}
The benchmark result is:
BenchmarkTime1-8 17705235 65.90 ns/op
BenchmarkTime2-8 38601799 29.68 ns/op