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Diffstat (limited to 'src/pkg/go/doc/testdata/benchmark.go')
-rw-r--r-- | src/pkg/go/doc/testdata/benchmark.go | 293 |
1 files changed, 0 insertions, 293 deletions
diff --git a/src/pkg/go/doc/testdata/benchmark.go b/src/pkg/go/doc/testdata/benchmark.go deleted file mode 100644 index 905e49644..000000000 --- a/src/pkg/go/doc/testdata/benchmark.go +++ /dev/null @@ -1,293 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package testing - -import ( - "flag" - "fmt" - "os" - "runtime" - "time" -) - -var matchBenchmarks = flag.String("test.bench", "", "regular expression to select benchmarks to run") -var benchTime = flag.Duration("test.benchtime", 1*time.Second, "approximate run time for each benchmark") - -// An internal type but exported because it is cross-package; part of the implementation -// of go test. -type InternalBenchmark struct { - Name string - F func(b *B) -} - -// B is a type passed to Benchmark functions to manage benchmark -// timing and to specify the number of iterations to run. -type B struct { - common - N int - benchmark InternalBenchmark - bytes int64 - timerOn bool - result BenchmarkResult -} - -// StartTimer starts timing a test. This function is called automatically -// before a benchmark starts, but it can also used to resume timing after -// a call to StopTimer. -func (b *B) StartTimer() { - if !b.timerOn { - b.start = time.Now() - b.timerOn = true - } -} - -// StopTimer stops timing a test. This can be used to pause the timer -// while performing complex initialization that you don't -// want to measure. -func (b *B) StopTimer() { - if b.timerOn { - b.duration += time.Now().Sub(b.start) - b.timerOn = false - } -} - -// ResetTimer sets the elapsed benchmark time to zero. -// It does not affect whether the timer is running. -func (b *B) ResetTimer() { - if b.timerOn { - b.start = time.Now() - } - b.duration = 0 -} - -// SetBytes records the number of bytes processed in a single operation. -// If this is called, the benchmark will report ns/op and MB/s. -func (b *B) SetBytes(n int64) { b.bytes = n } - -func (b *B) nsPerOp() int64 { - if b.N <= 0 { - return 0 - } - return b.duration.Nanoseconds() / int64(b.N) -} - -// runN runs a single benchmark for the specified number of iterations. -func (b *B) runN(n int) { - // Try to get a comparable environment for each run - // by clearing garbage from previous runs. - runtime.GC() - b.N = n - b.ResetTimer() - b.StartTimer() - b.benchmark.F(b) - b.StopTimer() -} - -func min(x, y int) int { - if x > y { - return y - } - return x -} - -func max(x, y int) int { - if x < y { - return y - } - return x -} - -// roundDown10 rounds a number down to the nearest power of 10. -func roundDown10(n int) int { - var tens = 0 - // tens = floor(log_10(n)) - for n > 10 { - n = n / 10 - tens++ - } - // result = 10^tens - result := 1 - for i := 0; i < tens; i++ { - result *= 10 - } - return result -} - -// roundUp rounds x up to a number of the form [1eX, 2eX, 5eX]. -func roundUp(n int) int { - base := roundDown10(n) - if n < (2 * base) { - return 2 * base - } - if n < (5 * base) { - return 5 * base - } - return 10 * base -} - -// run times the benchmark function in a separate goroutine. -func (b *B) run() BenchmarkResult { - go b.launch() - <-b.signal - return b.result -} - -// launch launches the benchmark function. It gradually increases the number -// of benchmark iterations until the benchmark runs for a second in order -// to get a reasonable measurement. It prints timing information in this form -// testing.BenchmarkHello 100000 19 ns/op -// launch is run by the fun function as a separate goroutine. -func (b *B) launch() { - // Run the benchmark for a single iteration in case it's expensive. - n := 1 - - // Signal that we're done whether we return normally - // or by FailNow's runtime.Goexit. - defer func() { - b.signal <- b - }() - - b.runN(n) - // Run the benchmark for at least the specified amount of time. - d := *benchTime - for !b.failed && b.duration < d && n < 1e9 { - last := n - // Predict iterations/sec. - if b.nsPerOp() == 0 { - n = 1e9 - } else { - n = int(d.Nanoseconds() / b.nsPerOp()) - } - // Run more iterations than we think we'll need for a second (1.5x). - // Don't grow too fast in case we had timing errors previously. - // Be sure to run at least one more than last time. - n = max(min(n+n/2, 100*last), last+1) - // Round up to something easy to read. - n = roundUp(n) - b.runN(n) - } - b.result = BenchmarkResult{b.N, b.duration, b.bytes} -} - -// The results of a benchmark run. -type BenchmarkResult struct { - N int // The number of iterations. - T time.Duration // The total time taken. - Bytes int64 // Bytes processed in one iteration. -} - -func (r BenchmarkResult) NsPerOp() int64 { - if r.N <= 0 { - return 0 - } - return r.T.Nanoseconds() / int64(r.N) -} - -func (r BenchmarkResult) mbPerSec() float64 { - if r.Bytes <= 0 || r.T <= 0 || r.N <= 0 { - return 0 - } - return (float64(r.Bytes) * float64(r.N) / 1e6) / r.T.Seconds() -} - -func (r BenchmarkResult) String() string { - mbs := r.mbPerSec() - mb := "" - if mbs != 0 { - mb = fmt.Sprintf("\t%7.2f MB/s", mbs) - } - nsop := r.NsPerOp() - ns := fmt.Sprintf("%10d ns/op", nsop) - if r.N > 0 && nsop < 100 { - // The format specifiers here make sure that - // the ones digits line up for all three possible formats. - if nsop < 10 { - ns = fmt.Sprintf("%13.2f ns/op", float64(r.T.Nanoseconds())/float64(r.N)) - } else { - ns = fmt.Sprintf("%12.1f ns/op", float64(r.T.Nanoseconds())/float64(r.N)) - } - } - return fmt.Sprintf("%8d\t%s%s", r.N, ns, mb) -} - -// An internal function but exported because it is cross-package; part of the implementation -// of go test. -func RunBenchmarks(matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) { - // If no flag was specified, don't run benchmarks. - if len(*matchBenchmarks) == 0 { - return - } - for _, Benchmark := range benchmarks { - matched, err := matchString(*matchBenchmarks, Benchmark.Name) - if err != nil { - fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.bench: %s\n", err) - os.Exit(1) - } - if !matched { - continue - } - for _, procs := range cpuList { - runtime.GOMAXPROCS(procs) - b := &B{ - common: common{ - signal: make(chan interface{}), - }, - benchmark: Benchmark, - } - benchName := Benchmark.Name - if procs != 1 { - benchName = fmt.Sprintf("%s-%d", Benchmark.Name, procs) - } - fmt.Printf("%s\t", benchName) - r := b.run() - if b.failed { - // The output could be very long here, but probably isn't. - // We print it all, regardless, because we don't want to trim the reason - // the benchmark failed. - fmt.Printf("--- FAIL: %s\n%s", benchName, b.output) - continue - } - fmt.Printf("%v\n", r) - // Unlike with tests, we ignore the -chatty flag and always print output for - // benchmarks since the output generation time will skew the results. - if len(b.output) > 0 { - b.trimOutput() - fmt.Printf("--- BENCH: %s\n%s", benchName, b.output) - } - if p := runtime.GOMAXPROCS(-1); p != procs { - fmt.Fprintf(os.Stderr, "testing: %s left GOMAXPROCS set to %d\n", benchName, p) - } - } - } -} - -// trimOutput shortens the output from a benchmark, which can be very long. -func (b *B) trimOutput() { - // The output is likely to appear multiple times because the benchmark - // is run multiple times, but at least it will be seen. This is not a big deal - // because benchmarks rarely print, but just in case, we trim it if it's too long. - const maxNewlines = 10 - for nlCount, j := 0, 0; j < len(b.output); j++ { - if b.output[j] == '\n' { - nlCount++ - if nlCount >= maxNewlines { - b.output = append(b.output[:j], "\n\t... [output truncated]\n"...) - break - } - } - } -} - -// Benchmark benchmarks a single function. Useful for creating -// custom benchmarks that do not use go test. -func Benchmark(f func(b *B)) BenchmarkResult { - b := &B{ - common: common{ - signal: make(chan interface{}), - }, - benchmark: InternalBenchmark{"", f}, - } - return b.run() -} |