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main.go
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main.go
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// Copyright 2015 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Write out a file of a certain size, close it, then measure the performance
// of doing the following:
//
// 1. Open the file.
// 2. Read it from start to end with a configurable buffer size.
//
package main
import (
"crypto/rand"
"errors"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"sort"
"time"
"github.com/googlecloudplatform/gcsfuse/benchmarks/internal/format"
"github.com/googlecloudplatform/gcsfuse/benchmarks/internal/percentile"
)
var fDir = flag.String("dir", "", "Directory within which to write the file.")
var fDuration = flag.Duration("duration", 10*time.Second, "How long to run.")
var fFileSize = flag.Int64("file_size", 1<<26, "Size of file to use.")
var fReadSize = flag.Int64("read_size", 1<<20, "Size of each call to read(2).")
////////////////////////////////////////////////////////////////////////
// main logic
////////////////////////////////////////////////////////////////////////
func run() (err error) {
if *fDir == "" {
err = errors.New("You must set --dir.")
return
}
// Create a temporary file.
log.Printf("Creating a temporary file in %s.", *fDir)
f, err := ioutil.TempFile(*fDir, "sequential_read")
if err != nil {
err = fmt.Errorf("TempFile: %v", err)
return
}
path := f.Name()
// Make sure we clean it up later.
defer func() {
log.Printf("Deleting %s.", path)
os.Remove(path)
}()
// Fill it with random content.
log.Printf("Writing %d random bytes.", *fFileSize)
_, err = io.Copy(f, io.LimitReader(rand.Reader, *fFileSize))
if err != nil {
err = fmt.Errorf("Copying random bytes: %v", err)
return
}
// Finish off the file.
err = f.Close()
if err != nil {
err = fmt.Errorf("Closing file: %v", err)
return
}
// Run several iterations.
log.Printf("Measuring for %v...", *fDuration)
var fullFileRead percentile.DurationSlice
var singleReadCall percentile.DurationSlice
buf := make([]byte, *fReadSize)
overallStartTime := time.Now()
for len(fullFileRead) == 0 || time.Since(overallStartTime) < *fDuration {
// Open the file for reading.
f, err = os.Open(path)
if err != nil {
err = fmt.Errorf("Opening file: %v", err)
return
}
// Read the whole thing.
fileStartTime := time.Now()
for err == nil {
readStartTime := time.Now()
_, err = f.Read(buf)
singleReadCall = append(singleReadCall, time.Since(readStartTime))
}
fullFileRead = append(fullFileRead, time.Since(fileStartTime))
switch {
case err == io.EOF:
err = nil
case err != nil:
err = fmt.Errorf("Reading: %v", err)
return
}
// Close the file.
err = f.Close()
if err != nil {
err = fmt.Errorf("Closing file after reading: %v", err)
return
}
}
sort.Sort(fullFileRead)
sort.Sort(singleReadCall)
log.Printf(
"Read the file %d times, using %d calls to read(2).",
len(fullFileRead),
len(singleReadCall))
// Report.
ptiles := []int{50, 90, 98}
reportSlice := func(
name string,
bytesPerObservation int64,
observations percentile.DurationSlice) {
fmt.Printf("\n%s:\n", name)
for _, ptile := range ptiles {
d := percentile.Duration(observations, ptile)
seconds := float64(d) / float64(time.Second)
bandwidthBytesPerSec := float64(bytesPerObservation) / seconds
fmt.Printf(
" %02dth ptile: %10v (%s/s)\n",
ptile,
d,
format.Bytes(bandwidthBytesPerSec))
}
}
reportSlice("Full-file read times", *fFileSize, fullFileRead)
reportSlice("read(2) latencies", *fReadSize, singleReadCall)
fmt.Println()
return
}
func main() {
log.SetFlags(log.Lmicroseconds | log.Lshortfile)
flag.Parse()
err := run()
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}