linux - IOzone输出中的 "Min xfer"和 "throughput"是什么意思

Question

我是 IOzone 的新用户，当我使用以下命令运行 IOzone 时:./iozone -i 0 -i 1 -t 2 -T，它会生成以下结果(部分):

Command line used: ./iozone -i 0 -i 1 -t 2 -T
Output is in Kbytes/sec
Time Resolution = 0.000001 seconds.
Processor cache size set to 1024 Kbytes.
Processor cache line size set to 32 bytes.
File stride size set to 17 * record size.
Throughput test with 2 threads
Each thread writes a 512 Kbyte file in 4 Kbyte records

Children see throughput for  2 initial writers  =  650943.69 KB/sec
Parent sees throughput for  2 initial writers   =   13090.24 KB/sec
Min throughput per thread           =  275299.72 KB/sec 
Max throughput per thread           =  375643.97 KB/sec
Avg throughput per thread           =  325471.84 KB/sec
Min xfer                    =     356.00 KB

Children see throughput for  2 rewriters    = 1375881.50 KB/sec
Parent sees throughput for  2 rewriters     =   10523.74 KB/sec                                                
Min throughput per thread           = 1375881.50 KB/sec 
Max throughput per thread           = 1375881.50 KB/sec
Avg throughput per thread           =  687940.75 KB/sec
Min xfer                    =     512.00 KB

Children see throughput for  2 readers      = 2169601.25 KB/sec
Parent sees throughput for  2 readers       =   27753.94 KB/sec
Min throughput per thread           = 2169601.25 KB/sec 
Max throughput per thread           = 2169601.25 KB/sec
Avg throughput per thread           = 1084800.62 KB/sec
Min xfer                    =     512.00 KB

Children see throughput for 2 re-readers    = 2572435.25 KB/sec
Parent sees throughput for 2 re-readers     =   26311.78 KB/sec
Min throughput per thread           = 2572435.25 KB/sec 
Max throughput per thread           = 2572435.25 KB/sec
Avg throughput per thread           = 1286217.62 KB/sec
Min xfer                    =     512.00 KB

iozone test complete.

我对“吞吐量”和“最小 xfer”的含义感到困惑，有人可以帮助我吗？顺便问一下，为什么从 child 和 parent 那里看到的吞吐量不同？谢谢!

Answer 1

Min xfer是指一次写入的最小数据量。 “每个线程在 4 KB 的记录中写入一个 512 KB 的文件”

因此，如果 Min xfer 为 512.00 KB，它会立即将整个实际文件写入磁盘(将所有 4 KB 记录组合在一起)。

由于操作系统 I/O 缓冲，子进程和父进程的吞吐量不同。 iozone 不会强制直接(非缓冲)读取或写入吞吐量测试。您真正测试的是系统的缓冲区缓存 + 磁盘缓存 + 磁盘速度组合。