以编程方式测量磁盘 IO

Question

我想以编程方式测量给定时间跨度内与磁盘 io 相关的一些数字。这意味着我不想生成像 iostat 这样的进程来获取我的数字，而是更喜欢从 proc 等读取内容。

我需要知道：

• 写入磁盘的块数
• 从磁盘读取的块数
• 从磁盘读取但在磁盘缓存中找到的块数
• 即将写入磁盘但尚未写入的块数，以了解我可能期望的成功 IO 数量。

如果我只通过磁盘或分区获取这些信息……那就更好了，因为我不需要知道我从 proc 读取了多少信息。

如果我还知道进程等待 IO 完成的时间......甚至更好。

这是否可以通过某些 IO 调用或通过读取和解析 /proc 文件来实现？

Answer 1

iostat 读取来源/proc/diskstats- 我无法告诉您哪一列对应于什么。那需要一点调查。此外，如果您想获取有关特定进程的更多信息，请/proc/[processID]包含与该进程相关的信息，例如 io 和 mem

文件中的一行如下所示：

8    0 sda 1576985 366566 29817737 8671588 4847477 21489330 210704848 14116392 0 14120880 22772188

来自/usr/src/linux-*/Documentation/iostats.txt：

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  6 -- # of writes merged
    See the description of field 2.
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.