[英]Calculating Disk Read/Write in Linux with C++
My requirement is to profile current process disk read/write operations with total disk read/write operations (or amount of data read/written). 我的要求是使用总磁盘读/写操作(或读/写的数据量)来分析当前进程磁盘的读/写操作。 I need to take samples evry second and plot a graph between these two.
我需要第二次取样并在这两者之间绘制图表。 I need to do this on Linux (Ubuntu 12.10) in c++.
我需要在c ++中的Linux(Ubuntu 12.10)上执行此操作。
Are there any APIs/Tools available for this task ? 是否有任何API /工具可用于此任务? I found one tool namely
iotop
but I am not sure how to use this for current process vs system wide usage. 我找到了一个工具
iotop
但是我不确定如何在当前进程和系统范围内使用该工具。
Thank You 谢谢
You can read the file /proc/diskstats
every second. 您可以
/proc/diskstats
读取文件/proc/diskstats
。 Each line represents one device. 每行代表一个设备。
From kernel's "Documentation/iostat.txt": 从内核的“ Documentation / iostat.txt”中:
Field 1 -- # of reads completed
This is the total number of reads completed successfully.
Field 2 -- # of reads merged, field 6 -- # of writes merged
Reads and writes which are adjacent to each other may be merged for
efficiency. Thus two 4K reads may become one 8K read before it is
ultimately handed to the disk, and so it will be counted (and queued)
as only one I/O. This field lets you know how often this was done.
Field 3 -- # of sectors read
This is the total number of sectors read successfully.
Field 4 -- # of milliseconds spent reading
This is the total number of milliseconds spent by all reads (as
measured from __make_request() to end_that_request_last()).
Field 5 -- # of writes completed
This is the total number of writes completed successfully.
Field 7 -- # of sectors written
This is the total number of sectors written successfully.
Field 8 -- # of milliseconds spent writing
This is the total number of milliseconds spent by all writes (as
measured from __make_request() to end_that_request_last()).
Field 9 -- # of I/Os currently in progress
The only field that should go to zero. Incremented as requests are
given to appropriate struct request_queue and decremented as they finish.
Field 10 -- # of milliseconds spent doing I/Os
This field increases so long as field 9 is nonzero.
Field 11 -- weighted # of milliseconds spent doing I/Os
This field is incremented at each I/O start, I/O completion, I/O
merge, or read of these stats by the number of I/Os in progress
(field 9) times the number of milliseconds spent doing I/O since the
last update of this field. This can provide an easy measure of both
I/O completion time and the backlog that may be accumulating.
For each process, you can get use /proc/<pid>/io
, which produces something like this: 对于每个进程,您都可以使用
/proc/<pid>/io
,它会生成如下内容:
rchar: 2012
wchar: 0
syscr: 7
syscw: 0
read_bytes: 0
write_bytes: 0
cancelled_write_bytes: 0
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