golang的磁盘写入性能

  • Z时代
  • 2024-01-10
  • 分类：问答

在以下代码中，我使用golang中的bufio将消息写入文件。我的磁盘I/O速度约为1000M/s。奇怪的是，当写入文件的大小小于20G时，写入速度大约为800M〜900M每秒，比I/O速度略低一点。但是，当文件大小超过21G时，我发现写入速度大约为每秒200M，远远低于I/O速度。我不知道为什么，有人可以帮助我？谢谢。golang的磁盘写入性能

package main 
import "fmt" 
import (
    "os" 
    "time" 
    "flag" 
    "bufio" 
) 
func main() { 
    var pRound = flag.Int64("round", 3500000, "loop round") 
    flag.Parse() 
    var message string 
    for i := 0; i < 1024; i++ { 
     message += "1234567890" 
    } 
    message += "\n" 
    f, err := os.OpenFile("server", os.O_CREATE|os.O_APPEND|os.O_RDWR, 0666) 
    if err != nil { 
     fmt.Println(err) 
     return 
    } 
    w := bufio.NewWriter(f) 
    var i int64 = 0 
    round := *pRound 
    start := time.Now() 
    for i = 0; i < round; i++ { 
     w.WriteString(message) 
    } 
    w.Flush() 
    f.Close() 
    end := time.Now() 
    nanoseconds := end.Sub(start).Nanoseconds() 
    speed := 1000000000 * round/nanoseconds 
    fmt.Printf("round: %v\n", round) 
    fmt.Printf("Nanoseconds: %v\n", nanoseconds) 
    fmt.Printf("speed: %v\n", speed) 
}

我想我已经问过一个愚蠢的问题。关于Vorsprung的回应，我在这里展示了我的C代码。我用C语言再次测试它。我用go语言找到了相同的结果。我的测试结果是：

./a.out 10000 
seconds: 7 
milliseconds: 260910 
total: 10485760000 Bytes 
total: 10000 M 
total: 9.76562 G 
speed: 1377.24 M/s 
./a.out 20000 
seconds: 24 
milliseconds: 7249 
total: 20971520000 Bytes 
total: 20000 M 
total: 19.5312 G 
speed: 833.082 M/s 
./a.out 30000 
seconds: 80 
milliseconds: 518970 
total: 31457280000 Bytes 
total: 30000 M 
total: 29.2969 G 
speed: 372.583 M/s 
./a.out 40000 
seconds: 134 
milliseconds: 615910 
total: 41943040000 Bytes 
total: 40000 M 
total: 39.0625 G 
speed: 297.142 M/s

以下是我的C代码：

#include <fcntl.h> 
#include <errno.h> 
#include <limits.h> 
#include <sys/uio.h> 
#include <time.h> 
#include <sys/time.h> 
#include <iostream> 
#include <string.h> 
#include <stdlib.h> 
int main(int argc, char* argv[]) { 
    if (argc != 2) { 
    std::cout << "usage: " << argv[0] << " round" << std::endl; 
    return -1; 
    } 
    int round = atoi(argv[1]); 
    int fd = open("file.data", O_CREAT | O_APPEND | O_RDWR, 0666); 
    if (fd == -1) { 
    std::cout << "open file error: " << strerror(errno) << std::endl; 
    return -1; 
    } 
    struct iovec vec[IOV_MAX]; 
    int len = 1024; 
    for (int i = 0; i < IOV_MAX; i++) { 
    vec[i].iov_base = new char[len]; 
    vec[i].iov_len = len; 
    char *buf = NULL; 
    for (int j = 0; j < len - 1; j++) { 
     buf = (char*)vec[i].iov_base; 
     buf[j] = j % 10 + '1'; 
    } 
    buf[len - 1] = '\n'; 
    } 
    timeval tv1; 
    gettimeofday(&tv1, NULL); 
    for (int i = 0; i < round; i++) { 
    writev(fd, vec, IOV_MAX); 
    } 
    close(fd); 
    timeval tv2; 
    gettimeofday(&tv2, NULL); 
    for (int i = 0; i < IOV_MAX; i++) { 
    char* buf = (char*)vec[i].iov_base; 
    delete[] buf; 
    } 
    std::cout << "seconds: " << tv2.tv_sec - tv1.tv_sec << std::endl; 
    std::cout << "milliseconds: " << tv2.tv_usec - tv1.tv_usec << std::endl; 
    int64_t total = int64_t(len) * IOV_MAX * round; 
    float t = (tv2.tv_sec - tv1.tv_sec) * 1000000.0 + (tv2.tv_usec - tv1.tv_usec); 
    float speed = 1000000.0 * total/t/1024/1024; 
    std::cout << "total: " << total << " Bytes" << std::endl; 
    std::cout << "total: " << total/1024.0/1024.0 << " M" << std::endl; 
    std::cout << "total: " << total/1024.0/1024.0/1024.0 << " G" << std::endl; 
    std::cout << "speed: " << speed << " M/s" << std::endl; 
    return 0; 
}

现在我diskio.go测试结果显示在这里。因为我不知道如何评论简单阅读的结果，所以我在这里展示它。

time ./diskio -size=4 
written: 4294967296B 26237051975ns 4.29GB 26.24s 163.70MB/s 
real 0m26.980s 
user 0m0.397s 
sys  0m4.874s 
time ./diskio -size=8 
written: 8589934592B 57803019028ns 8.59GB 57.80s 148.61MB/s 
real 0m59.192s 
user 0m0.813s 
sys  0m9.607s 
time ./diskio -size=10 
written: 10737418240B 68331989999ns 10.74GB 68.33s 157.14MB/s 
real 1m10.288s 
user 0m0.946s 
sys  0m12.024s 
time ./diskio -size=20 
written: 21474836480B 141169506440ns 21.47GB 141.17s 152.12MB/s 
real 2m25.037s 
user 0m1.881s 
sys  0m24.029s 
time ./diskio -size=30 
written: 32212254720B 203807569664ns 32.21GB 203.81s 158.05MB/s 
real 3m29.345s 
user 0m2.925s 
sys  0m33.528s

diskio.go来自https://stackoverflow.com/a/47889346/5616809

我觉得我得到了答案，测试结果由磁盘缓冲区的原因造成的。我测试了我的硬盘速度使用hdparm表彰，而我得到这个：

hdparm -Tt /dev/sde1 
/dev/sde1: 
Timing cached reads: 18166 MB in 2.00 seconds = 9093.93 MB/sec 
Timing buffered disk reads: 584 MB in 3.01 seconds = 194.18 MB/sec

所以，也许我的程序书面方式字节缓冲区时，文件大小小于约18166M。之后，该程序正在写入磁盘，所以速度较慢。

回答：

我觉得我得到的回答这个问题。由于我的磁盘I/O速度约为194M/s，磁盘缓冲I/O约为9093M/s。但磁盘缓冲区大小约为18166M。所以当文件大小小于20G时写入速度会更快。我用这个命令来测试我的磁盘I/O速度：

hdparm -Tt /dev/sde1 
/dev/sde1: 
Timing cached reads: 18166 MB in 2.00 seconds = 9093.93 MB/sec 
Timing buffered disk reads: 584 MB in 3.01 seconds = 194.18 MB/sec

回答：

您的问题是无法重复的。你的代码有错误。

我们预计磁盘写入时间会受到很多因素的影响：程序，其他程序，操作系统，硬件等等。

启动独立的专用机器并运行diskio.go程序。你会得到什么结果？例如，我的机器上：

$ go build diskio.go 
$ time ./diskio -size=32 
written: 34359738368B 154333936544ns 34.36GB 154.33s 222.63MB/s 
real 2m35.323s 
user 0m6.418s 
sys  0m41.994s 
$ time ./diskio -size=16 
written: 17179869184B 77901269159ns 17.18GB 77.90s 220.53MB/s 
real 1m18.746s 
user 0m2.849s 
sys  0m21.721s 
$ time ./diskio -size=8 
written: 8589934592B 38940248134ns 8.59GB 38.94s 220.59MB/s 
real 0m39.625s 
user 0m1.719s 
sys  0m12.493s 
$ time ./diskio -size=1 
written: 1073741824B 4738082404ns 1.07GB 4.74s 226.62MB/s 
real 0m4.851s 
user 0m0.069s 
sys  0m0.755s 
$

正如预期的那样，很少有时间在节目中度过，更多的时间是在操作系统中度过的，大量的时间都花在等待在磁盘上。写入速度没有急剧变化。

diskio.go：

package main 
import (
    "bufio" 
    "flag" 
    "fmt" 
    "os" 
    "time" 
) 
func writeFile(fSize int64) error { 
    fName := `/home/peter/diskio` // test file 
    defer os.Remove(fName) 
    f, err := os.Create(fName) 
    if err != nil { 
     return err 
    } 
    const defaultBufSize = 4096 
    buf := make([]byte, defaultBufSize) 
    buf[len(buf)-1] = '\n' 
    w := bufio.NewWriterSize(f, len(buf)) 
    start := time.Now() 
    written := int64(0) 
    for i := int64(0); i < fSize; i += int64(len(buf)) { 
     nn, err := w.Write(buf) 
     written += int64(nn) 
     if err != nil { 
      return err 
     } 
    } 
    err = w.Flush() 
    if err != nil { 
     return err 
    } 
    err = f.Sync() 
    if err != nil { 
     return err 
    } 
    since := time.Since(start) 
    err = f.Close() 
    if err != nil { 
     return err 
    } 
    fmt.Printf("written: %dB %dns %.2fGB %.2fs %.2fMB/s\n", 
     written, since, 
     float64(written)/1000000000, float64(since)/float64(time.Second), 
     (float64(written)/1000000)/(float64(since)/float64(time.Second)), 
    ) 
    return nil 
} 
var size = flag.Int("size", 8, "file size in GiB") 
func main() { 
    flag.Parse() 
    fSize := int64(*size) * (1024 * 1024 * 1024) 
    err := writeFile(fSize) 
    if err != nil { 
     fmt.Fprintln(os.Stderr, fSize, err) 
    } 
}

游乐场：https://play.golang.org/p/vnjnpgMzsV

以上是 golang的磁盘写入性能 的全部内容， 来源链接： utcz.com/qa/261840.html

回到顶部