tools/src/bench/bench.go - dawn - Git at Google

 // Copyright 2022 The Dawn & Tint Authors
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are met:
 //
 // 1. Redistributions of source code must retain the above copyright notice, this
 //    list of conditions and the following disclaimer.
 //
 // 2. Redistributions in binary form must reproduce the above copyright notice,
 //    this list of conditions and the following disclaimer in the documentation
 //    and/or other materials provided with the distribution.
 //
 // 3. Neither the name of the copyright holder nor the names of its
 //    contributors may be used to endorse or promote products derived from
 //    this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 // Package bench provides types and methods for parsing Google benchmark results.
 package bench

 import (
 	"encoding/json"
 	"errors"
 	"fmt"
 	"regexp"
 	"sort"
 	"strconv"
 	"strings"
 	"time"
 	"unicode/utf8"
 )

 // Run holds all the benchmark results for a run, along with the context
 // information for the run.
 type Run struct {
 	Benchmarks []Benchmark
 	Context    *Context
 }

 // Context provides information about the environment used to perform the
 // benchmark.
 type Context struct {
 	Date              time.Time
 	HostName          string
 	Executable        string
 	NumCPUs           int
 	MhzPerCPU         int
 	CPUScalingEnabled bool
 	Caches            []ContextCache
 	LoadAvg           []float32
 	LibraryBuildType  string
 }

 // ContextCache holds information about one of the system caches.
 type ContextCache struct {
 	Type       string
 	Level      int
 	Size       int
 	NumSharing int
 }

 // Benchmark holds the results of a single benchmark test.
 type Benchmark struct {
 	Name          string
 	Duration      time.Duration
 	AggregateType AggregateType
 }

 // AggregateType is an enumerator of benchmark aggregate types.
 type AggregateType string

 // Enumerator values of AggregateType
 const (
 	NonAggregate AggregateType = "NonAggregate"
 	Mean         AggregateType = "mean"
 	Median       AggregateType = "median"
 	Stddev       AggregateType = "stddev"
 )

 // Parse parses the benchmark results from the string s.
 // Parse will handle the json and 'console' formats.
 func Parse(s string) (Run, error) {
 	type Parser = func(s string) (Run, error)
 	for _, parser := range []Parser{parseConsole, parseJSON} {
 		r, err := parser(s)
 		switch err {
 		case nil:
 			return r, nil
 		case errWrongFormat:
 		default:
 			return Run{}, err
 		}
 	}

 	return Run{}, errors.New("Unrecognised file format")
 }

 var errWrongFormat = errors.New("Wrong format")
 var consoleLineRE = regexp.MustCompile(`([\w/:]+)\s+([0-9]+(?:.[0-9]+)?) ns\s+[0-9]+(?:.[0-9]+) ns\s+([0-9]+)`)

 func parseConsole(s string) (Run, error) {
 	blocks := strings.Split(s, "------------------------------------------------------------------------------------------")
 	if len(blocks) != 3 {
 		return Run{}, errWrongFormat
 	}

 	lines := strings.Split(blocks[2], "\n")
 	b := make([]Benchmark, 0, len(lines))

 	for _, line := range lines {
 		if len(line) == 0 {
 			continue
 		}
 		matches := consoleLineRE.FindStringSubmatch(line)
 		if len(matches) != 4 {
 			return Run{}, fmt.Errorf("Unable to parse the line:\n" + line)
 		}
 		ns, err := strconv.ParseFloat(matches[2], 64)
 		if err != nil {
 			return Run{}, fmt.Errorf("Unable to parse the duration: " + matches[2])
 		}

 		b = append(b, Benchmark{
 			Name:     trimAggregateSuffix(matches[1]),
 			Duration: time.Nanosecond * time.Duration(ns),
 		})
 	}
 	return Run{Benchmarks: b}, nil
 }

 func parseJSON(s string) (Run, error) {
 	type Data struct {
 		Context struct {
 			Date              time.Time `json:"date"`
 			HostName          string    `json:"host_name"`
 			Executable        string    `json:"executable"`
 			NumCPUs           int       `json:"num_cpus"`
 			MhzPerCPU         int       `json:"mhz_per_cpu"`
 			CPUScalingEnabled bool      `json:"cpu_scaling_enabled"`
 			LoadAvg           []float32 `json:"load_avg"`
 			LibraryBuildType  string    `json:"library_build_type"`
 			Caches            []struct {
 				Type       string `json:"type"`
 				Level      int    `json:"level"`
 				Size       int    `json:"size"`
 				NumSharing int    `json:"num_sharing"`
 			} `json:"caches"`
 		} `json:"context"`
 		Benchmarks []struct {
 			Name          string        `json:"name"`
 			Time          float64       `json:"cpu_time"`
 			AggregateType AggregateType `json:"aggregate_name"`
 		} `json:"benchmarks"`
 	}
 	data := Data{}
 	d := json.NewDecoder(strings.NewReader(s))
 	if err := d.Decode(&data); err != nil {
 		return Run{}, err
 	}

 	out := Run{
 		Benchmarks: make([]Benchmark, len(data.Benchmarks)),
 		Context: &Context{
 			Date:              data.Context.Date,
 			HostName:          data.Context.HostName,
 			Executable:        data.Context.Executable,
 			NumCPUs:           data.Context.NumCPUs,
 			MhzPerCPU:         data.Context.MhzPerCPU,
 			CPUScalingEnabled: data.Context.CPUScalingEnabled,
 			LoadAvg:           data.Context.LoadAvg,
 			LibraryBuildType:  data.Context.LibraryBuildType,
 			Caches:            make([]ContextCache, len(data.Context.Caches)),
 		},
 	}
 	for i, c := range data.Context.Caches {
 		out.Context.Caches[i] = ContextCache{
 			Type:       c.Type,
 			Level:      c.Level,
 			Size:       c.Size,
 			NumSharing: c.NumSharing,
 		}
 	}
 	for i, b := range data.Benchmarks {
 		out.Benchmarks[i] = Benchmark{
 			Name:          trimAggregateSuffix(b.Name),
 			Duration:      time.Nanosecond * time.Duration(int64(b.Time)),
 			AggregateType: b.AggregateType,
 		}
 	}

 	return out, nil
 }

 // Diff describes the difference between two benchmarks
 type Diff struct {
 	TestName           string
 	Delta              time.Duration // Δ (A → B)
 	PercentChangeAB    float64       // % (A → B)
 	PercentChangeBA    float64       // % (B → A)
 	MultiplierChangeAB float64       // × (A → B)
 	MultiplierChangeBA float64       // × (B → A)
 	TimeA              time.Duration // A
 	TimeB              time.Duration // B
 }

 // Diffs is a list of Diff
 type Diffs []Diff

 // DiffFormat describes how a list of diffs should be formatted
 type DiffFormat struct {
 	TestName           bool
 	Delta              bool
 	PercentChangeAB    bool
 	PercentChangeBA    bool
 	MultiplierChangeAB bool
 	MultiplierChangeBA bool
 	TimeA              bool
 	TimeB              bool
 }

 func (diffs Diffs) Format(f DiffFormat) string {
 	if len(diffs) == 0 {
 		return "<no changes>"
 	}

 	type row []string

 	header := row{}
 	if f.TestName {
 		header = append(header, "Test name")
 	}
 	if f.Delta {
 		header = append(header, "Δ (A → B)")
 	}
 	if f.PercentChangeAB {
 		header = append(header, "% (A → B)")
 	}
 	if f.PercentChangeBA {
 		header = append(header, "% (B → A)")
 	}
 	if f.MultiplierChangeAB {
 		header = append(header, "× (A → B)")
 	}
 	if f.MultiplierChangeBA {
 		header = append(header, "× (B → A)")
 	}
 	if f.TimeA {
 		header = append(header, "A")
 	}
 	if f.TimeB {
 		header = append(header, "B")
 	}
 	if len(header) == 0 {
 		return ""
 	}

 	columns := []row{}
 	for _, d := range diffs {
 		r := make(row, 0, len(header))
 		if f.TestName {
 			r = append(r, d.TestName)
 		}
 		if f.Delta {
 			r = append(r, fmt.Sprintf("%v", d.Delta))
 		}
 		if f.PercentChangeAB {
 			r = append(r, fmt.Sprintf("%+2.1f%%", d.PercentChangeAB))
 		}
 		if f.PercentChangeBA {
 			r = append(r, fmt.Sprintf("%+2.1f%%", d.PercentChangeBA))
 		}
 		if f.MultiplierChangeAB {
 			r = append(r, fmt.Sprintf("%+.4f", d.MultiplierChangeAB))
 		}
 		if f.MultiplierChangeBA {
 			r = append(r, fmt.Sprintf("%+.4f", d.MultiplierChangeBA))
 		}
 		if f.TimeA {
 			r = append(r, fmt.Sprintf("%v", d.TimeA))
 		}
 		if f.TimeB {
 			r = append(r, fmt.Sprintf("%v", d.TimeB))
 		}
 		columns = append(columns, r)
 	}

 	// measure
 	widths := make([]int, len(header))
 	for i, h := range header {
 		widths[i] = utf8.RuneCountInString(h)
 	}
 	for _, row := range columns {
 		for i, cell := range row {
 			l := utf8.RuneCountInString(cell)
 			if widths[i] < l {
 				widths[i] = l
 			}
 		}
 	}

 	pad := func(s string, i int) string {
 		if n := i - utf8.RuneCountInString(s); n > 0 {
 			return s + strings.Repeat(" ", n)
 		}
 		return s
 	}

 	// Draw table
 	b := &strings.Builder{}

 	horizontal_bar := func() {
 		for i := range header {
 			fmt.Fprintf(b, "+%v", strings.Repeat("-", 2+widths[i]))
 		}
 		fmt.Fprintln(b, "+")
 	}

 	horizontal_bar()

 	for i, h := range header {
 		fmt.Fprintf(b, "| %v ", pad(h, widths[i]))
 	}
 	fmt.Fprintln(b, "|")

 	horizontal_bar()

 	for _, row := range columns {
 		for i, cell := range row {
 			fmt.Fprintf(b, "| %v ", pad(cell, widths[i]))
 		}
 		fmt.Fprintln(b, "|")
 	}

 	horizontal_bar()

 	return b.String()
 }

 // Compare returns a string describing differences in the two benchmarks
 // Absolute benchmark differences less than minDiff are omitted
 // Absolute relative differences between [1, 1+x] are omitted
 func Compare(a, b []Benchmark, minDiff time.Duration, minRelDiff float64) Diffs {
 	type times struct {
 		a time.Duration
 		b time.Duration
 	}
 	byName := map[string]times{}
 	for _, test := range a {
 		byName[test.Name] = times{a: test.Duration}
 	}
 	for _, test := range b {
 		t := byName[test.Name]
 		t.b = test.Duration
 		byName[test.Name] = t
 	}

 	type delta struct {
 		name       string
 		times      times
 		relDiff    float64
 		absRelDiff float64
 	}
 	deltas := []delta{}
 	for name, times := range byName {
 		if times.a == 0 || times.b == 0 {
 			continue // Assuming test was missing from a or b
 		}
 		diff := times.b - times.a
 		absDiff := diff
 		if absDiff < 0 {
 			absDiff = -absDiff
 		}
 		if absDiff < minDiff {
 			continue
 		}

 		relDiff := float64(times.b) / float64(times.a)
 		absRelDiff := relDiff
 		if absRelDiff < 1 {
 			absRelDiff = 1.0 / absRelDiff
 		}
 		if absRelDiff < (1.0 + minRelDiff) {
 			continue
 		}

 		d := delta{
 			name:       name,
 			times:      times,
 			relDiff:    relDiff,
 			absRelDiff: absRelDiff,
 		}
 		deltas = append(deltas, d)
 	}

 	sort.Slice(deltas, func(i, j int) bool { return deltas[j].relDiff < deltas[i].relDiff })

 	out := make(Diffs, len(deltas))

 	for i, delta := range deltas {
 		a2b := delta.times.b - delta.times.a
 		out[i] = Diff{
 			TestName:           delta.name,
 			Delta:              a2b,
 			PercentChangeAB:    100 * float64(a2b) / float64(delta.times.a),
 			PercentChangeBA:    100 * float64(-a2b) / float64(delta.times.b),
 			MultiplierChangeAB: float64(delta.times.b) / float64(delta.times.a),
 			MultiplierChangeBA: float64(delta.times.a) / float64(delta.times.b),
 			TimeA:              delta.times.a,
 			TimeB:              delta.times.b,
 		}
 	}
 	return out
 }

 func trimAggregateSuffix(name string) string {
 	name = strings.TrimSuffix(name, "_stddev")
 	name = strings.TrimSuffix(name, "_mean")
 	name = strings.TrimSuffix(name, "_median")
 	return name
 }
	// Copyright 2022 The Dawn & Tint Authors
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are met:
	//
	// 1. Redistributions of source code must retain the above copyright notice, this
	// list of conditions and the following disclaimer.
	//
	// 2. Redistributions in binary form must reproduce the above copyright notice,
	// this list of conditions and the following disclaimer in the documentation
	// and/or other materials provided with the distribution.
	//
	// 3. Neither the name of the copyright holder nor the names of its
	// contributors may be used to endorse or promote products derived from
	// this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
	// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
	// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	// Package bench provides types and methods for parsing Google benchmark results.
	package bench

	import (
	"encoding/json"
	"errors"
	"fmt"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"
	"unicode/utf8"
	)

	// Run holds all the benchmark results for a run, along with the context
	// information for the run.
	type Run struct {
	Benchmarks []Benchmark
	Context *Context
	}

	// Context provides information about the environment used to perform the
	// benchmark.
	type Context struct {
	Date time.Time
	HostName string
	Executable string
	NumCPUs int
	MhzPerCPU int
	CPUScalingEnabled bool
	Caches []ContextCache
	LoadAvg []float32
	LibraryBuildType string
	}

	// ContextCache holds information about one of the system caches.
	type ContextCache struct {
	Type string
	Level int
	Size int
	NumSharing int
	}

	// Benchmark holds the results of a single benchmark test.
	type Benchmark struct {
	Name string
	Duration time.Duration
	AggregateType AggregateType
	}

	// AggregateType is an enumerator of benchmark aggregate types.
	type AggregateType string

	// Enumerator values of AggregateType
	const (
	NonAggregate AggregateType = "NonAggregate"
	Mean AggregateType = "mean"
	Median AggregateType = "median"
	Stddev AggregateType = "stddev"
	)

	// Parse parses the benchmark results from the string s.
	// Parse will handle the json and 'console' formats.
	func Parse(s string) (Run, error) {
	type Parser = func(s string) (Run, error)
	for _, parser := range []Parser{parseConsole, parseJSON} {
	r, err := parser(s)
	switch err {
	case nil:
	return r, nil
	case errWrongFormat:
	default:
	return Run{}, err
	}
	}

	return Run{}, errors.New("Unrecognised file format")
	}

	var errWrongFormat = errors.New("Wrong format")
	var consoleLineRE = regexp.MustCompile(`([\w/:]+)\s+([0-9]+(?:.[0-9]+)?) ns\s+[0-9]+(?:.[0-9]+) ns\s+([0-9]+)`)

	func parseConsole(s string) (Run, error) {
	blocks := strings.Split(s, "------------------------------------------------------------------------------------------")
	if len(blocks) != 3 {
	return Run{}, errWrongFormat
	}

	lines := strings.Split(blocks[2], "\n")
	b := make([]Benchmark, 0, len(lines))

	for _, line := range lines {
	if len(line) == 0 {
	continue
	}
	matches := consoleLineRE.FindStringSubmatch(line)
	if len(matches) != 4 {
	return Run{}, fmt.Errorf("Unable to parse the line:\n" + line)
	}
	ns, err := strconv.ParseFloat(matches[2], 64)
	if err != nil {
	return Run{}, fmt.Errorf("Unable to parse the duration: " + matches[2])
	}

	b = append(b, Benchmark{
	Name: trimAggregateSuffix(matches[1]),
	Duration: time.Nanosecond * time.Duration(ns),
	})
	}
	return Run{Benchmarks: b}, nil
	}

	func parseJSON(s string) (Run, error) {
	type Data struct {
	Context struct {
	Date time.Time `json:"date"`
	HostName string `json:"host_name"`
	Executable string `json:"executable"`
	NumCPUs int `json:"num_cpus"`
	MhzPerCPU int `json:"mhz_per_cpu"`
	CPUScalingEnabled bool `json:"cpu_scaling_enabled"`
	LoadAvg []float32 `json:"load_avg"`
	LibraryBuildType string `json:"library_build_type"`
	Caches []struct {
	Type string `json:"type"`
	Level int `json:"level"`
	Size int `json:"size"`
	NumSharing int `json:"num_sharing"`
	} `json:"caches"`
	} `json:"context"`
	Benchmarks []struct {
	Name string `json:"name"`
	Time float64 `json:"cpu_time"`
	AggregateType AggregateType `json:"aggregate_name"`
	} `json:"benchmarks"`
	}
	data := Data{}
	d := json.NewDecoder(strings.NewReader(s))
	if err := d.Decode(&data); err != nil {
	return Run{}, err
	}

	out := Run{
	Benchmarks: make([]Benchmark, len(data.Benchmarks)),
	Context: &Context{
	Date: data.Context.Date,
	HostName: data.Context.HostName,
	Executable: data.Context.Executable,
	NumCPUs: data.Context.NumCPUs,
	MhzPerCPU: data.Context.MhzPerCPU,
	CPUScalingEnabled: data.Context.CPUScalingEnabled,
	LoadAvg: data.Context.LoadAvg,
	LibraryBuildType: data.Context.LibraryBuildType,
	Caches: make([]ContextCache, len(data.Context.Caches)),
	},
	}
	for i, c := range data.Context.Caches {
	out.Context.Caches[i] = ContextCache{
	Type: c.Type,
	Level: c.Level,
	Size: c.Size,
	NumSharing: c.NumSharing,
	}
	}
	for i, b := range data.Benchmarks {
	out.Benchmarks[i] = Benchmark{
	Name: trimAggregateSuffix(b.Name),
	Duration: time.Nanosecond * time.Duration(int64(b.Time)),
	AggregateType: b.AggregateType,
	}
	}

	return out, nil
	}

	// Diff describes the difference between two benchmarks
	type Diff struct {
	TestName string
	Delta time.Duration // Δ (A → B)
	PercentChangeAB float64 // % (A → B)
	PercentChangeBA float64 // % (B → A)
	MultiplierChangeAB float64 // × (A → B)
	MultiplierChangeBA float64 // × (B → A)
	TimeA time.Duration // A
	TimeB time.Duration // B
	}

	// Diffs is a list of Diff
	type Diffs []Diff

	// DiffFormat describes how a list of diffs should be formatted
	type DiffFormat struct {
	TestName bool
	Delta bool
	PercentChangeAB bool
	PercentChangeBA bool
	MultiplierChangeAB bool
	MultiplierChangeBA bool
	TimeA bool
	TimeB bool
	}

	func (diffs Diffs) Format(f DiffFormat) string {
	if len(diffs) == 0 {
	return "<no changes>"
	}

	type row []string

	header := row{}
	if f.TestName {
	header = append(header, "Test name")
	}
	if f.Delta {
	header = append(header, "Δ (A → B)")
	}
	if f.PercentChangeAB {
	header = append(header, "% (A → B)")
	}
	if f.PercentChangeBA {
	header = append(header, "% (B → A)")
	}
	if f.MultiplierChangeAB {
	header = append(header, "× (A → B)")
	}
	if f.MultiplierChangeBA {
	header = append(header, "× (B → A)")
	}
	if f.TimeA {
	header = append(header, "A")
	}
	if f.TimeB {
	header = append(header, "B")
	}
	if len(header) == 0 {
	return ""
	}

	columns := []row{}
	for _, d := range diffs {
	r := make(row, 0, len(header))
	if f.TestName {
	r = append(r, d.TestName)
	}
	if f.Delta {
	r = append(r, fmt.Sprintf("%v", d.Delta))
	}
	if f.PercentChangeAB {
	r = append(r, fmt.Sprintf("%+2.1f%%", d.PercentChangeAB))
	}
	if f.PercentChangeBA {
	r = append(r, fmt.Sprintf("%+2.1f%%", d.PercentChangeBA))
	}
	if f.MultiplierChangeAB {
	r = append(r, fmt.Sprintf("%+.4f", d.MultiplierChangeAB))
	}
	if f.MultiplierChangeBA {
	r = append(r, fmt.Sprintf("%+.4f", d.MultiplierChangeBA))
	}
	if f.TimeA {
	r = append(r, fmt.Sprintf("%v", d.TimeA))
	}
	if f.TimeB {
	r = append(r, fmt.Sprintf("%v", d.TimeB))
	}
	columns = append(columns, r)
	}

	// measure
	widths := make([]int, len(header))
	for i, h := range header {
	widths[i] = utf8.RuneCountInString(h)
	}
	for _, row := range columns {
	for i, cell := range row {
	l := utf8.RuneCountInString(cell)
	if widths[i] < l {
	widths[i] = l
	}
	}
	}

	pad := func(s string, i int) string {
	if n := i - utf8.RuneCountInString(s); n > 0 {
	return s + strings.Repeat(" ", n)
	}
	return s
	}

	// Draw table
	b := &strings.Builder{}

	horizontal_bar := func() {
	for i := range header {
	fmt.Fprintf(b, "+%v", strings.Repeat("-", 2+widths[i]))
	}
	fmt.Fprintln(b, "+")
	}

	horizontal_bar()

	for i, h := range header {
	fmt.Fprintf(b, "\| %v ", pad(h, widths[i]))
	}
	fmt.Fprintln(b, "\|")

	horizontal_bar()

	for _, row := range columns {
	for i, cell := range row {
	fmt.Fprintf(b, "\| %v ", pad(cell, widths[i]))
	}
	fmt.Fprintln(b, "\|")
	}

	horizontal_bar()

	return b.String()
	}

	// Compare returns a string describing differences in the two benchmarks
	// Absolute benchmark differences less than minDiff are omitted
	// Absolute relative differences between [1, 1+x] are omitted
	func Compare(a, b []Benchmark, minDiff time.Duration, minRelDiff float64) Diffs {
	type times struct {
	a time.Duration
	b time.Duration
	}
	byName := map[string]times{}
	for _, test := range a {
	byName[test.Name] = times{a: test.Duration}
	}
	for _, test := range b {
	t := byName[test.Name]
	t.b = test.Duration
	byName[test.Name] = t
	}

	type delta struct {
	name string
	times times
	relDiff float64
	absRelDiff float64
	}
	deltas := []delta{}
	for name, times := range byName {
	if times.a == 0 \|\| times.b == 0 {
	continue // Assuming test was missing from a or b
	}
	diff := times.b - times.a
	absDiff := diff
	if absDiff < 0 {
	absDiff = -absDiff
	}
	if absDiff < minDiff {
	continue
	}

	relDiff := float64(times.b) / float64(times.a)
	absRelDiff := relDiff
	if absRelDiff < 1 {
	absRelDiff = 1.0 / absRelDiff
	}
	if absRelDiff < (1.0 + minRelDiff) {
	continue
	}

	d := delta{
	name: name,
	times: times,
	relDiff: relDiff,
	absRelDiff: absRelDiff,
	}
	deltas = append(deltas, d)
	}

	sort.Slice(deltas, func(i, j int) bool { return deltas[j].relDiff < deltas[i].relDiff })

	out := make(Diffs, len(deltas))

	for i, delta := range deltas {
	a2b := delta.times.b - delta.times.a
	out[i] = Diff{
	TestName: delta.name,
	Delta: a2b,
	PercentChangeAB: 100 * float64(a2b) / float64(delta.times.a),
	PercentChangeBA: 100 * float64(-a2b) / float64(delta.times.b),
	MultiplierChangeAB: float64(delta.times.b) / float64(delta.times.a),
	MultiplierChangeBA: float64(delta.times.a) / float64(delta.times.b),
	TimeA: delta.times.a,
	TimeB: delta.times.b,
	}
	}
	return out
	}

	func trimAggregateSuffix(name string) string {
	name = strings.TrimSuffix(name, "_stddev")
	name = strings.TrimSuffix(name, "_mean")
	name = strings.TrimSuffix(name, "_median")
	return name
	}