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標(biāo)題: io accounting 的問題 [打印本頁]
作者: dajun    時間: 2008-12-17 09:31
標(biāo)題: io accounting 的問題
和內(nèi)核沾點(diǎn)邊,來這里求助了,

我想在用戶層分別得到使用磁盤,cpu最高的幾個進(jìn)程(或者進(jìn)程組), 不知道該如何實(shí)現(xiàn),
linux下有個iotop能以類似top(1)的形式顯示進(jìn)程的I/O利用情況,但是那個軟件是python寫的,我讀起來很(非常)吃力,
他大致是先在從proc讀到進(jìn)程列表,然后又讀了 /proc/xxpid/status, 然后用netlink獲得某些進(jìn)程的taskstats

不清楚從proc pid status下他想讀什么,貌似是讀進(jìn)程的uid,gid之類的東東



  3. // /usr/include/linux/taskstats.h

  5. struct taskstats {

  7. ...
  8.         __u8        ac_flag;                /* Record flags */
  9.         __u8        ac_nice;                /* task_nice */

  11.         __u64        cpu_count __attribute__((aligned(8)));
  12.         __u64        cpu_delay_total;

  14.         /* Following four fields atomically updated using task->delays->lock */

  16.         /* Delay waiting for synchronous block I/O to complete
  17.          * does not account for delays in I/O submission
  18.          */
  19.         __u64        blkio_count;
  20.         __u64        blkio_delay_total;

  22.         /* Delay waiting for page fault I/O (swap in only) */
  23.         __u64        swapin_count;
  24.         __u64        swapin_delay_total;

  26.         /* cpu "wall-clock" running time
  27.          * On some architectures, value will adjust for cpu time stolen
  28.          * from the kernel in involuntary waits due to virtualization.
  29.          * Value is cumulative, in nanoseconds, without a corresponding count
  30.          * and wraps around to zero silently on overflow
  31.          */
  32.         __u64        cpu_run_real_total;

  34.         /* cpu "virtual" running time
  35.          * Uses time intervals seen by the kernel i.e. no adjustment
  36.          * for kernel's involuntary waits due to virtualization.
  37.          * Value is cumulative, in nanoseconds, without a corresponding count
  38.          * and wraps around to zero silently on overflow
  39.          */
  40.         __u64        cpu_run_virtual_total;
  41.         /* Delay accounting fields end */
  42.         /* version 1 ends here */

  44.         /* Basic Accounting Fields start */
  45.         char        ac_comm[TS_COMM_LEN];        /* Command name */
  46.         __u8        ac_sched __attribute__((aligned(8)));
  47.                                         /* Scheduling discipline */
  48.         __u8        ac_pad[3];
  49.         __u32        ac_uid __attribute__((aligned(8)));
  50.                                         /* User ID */
  51.         __u32        ac_gid;                        /* Group ID */
  52.         __u32        ac_pid;                        /* Process ID */
  53.         __u32        ac_ppid;                /* Parent process ID */
  54.         __u32        ac_btime;                /* Begin time [sec since 1970] */
  55.         __u64        ac_etime __attribute__((aligned(8)));
  56.                                         /* Elapsed time [usec] */
  57.         __u64        ac_utime;                /* User CPU time [usec] */
  58.         __u64        ac_stime;                /* SYstem CPU time [usec] */
  59.         __u64        ac_minflt;                /* Minor Page Fault Count */
  60.         __u64        ac_majflt;                /* Major Page Fault Count */
  61. ...

  63.         /* The following four fields are I/O statistics of a task. */
  64.         __u64        read_char;                /* bytes read */
  65.         __u64        write_char;                /* bytes written */
  66.         __u64        read_syscalls;                /* read syscalls */
  67.         __u64        write_syscalls;                /* write syscalls */
  68.         /* Extended accounting fields end */

  70. #define TASKSTATS_HAS_IO_ACCOUNTING
  71.         /* Per-task storage I/O accounting starts */
  72.         __u64        read_bytes;                /* bytes of read I/O */
  73.         __u64        write_bytes;                /* bytes of write I/O */
  74.         __u64        cancelled_write_bytes;        /* bytes of cancelled write I/O */

  76.         __u64  nvcsw;                        /* voluntary_ctxt_switches */
  77.         __u64  nivcsw;                        /* nonvoluntary_ctxt_switches */

  79.         /* time accounting for SMT machines */
  80.         __u64        ac_utimescaled;                /* utime scaled on frequency etc */
  81.         __u64        ac_stimescaled;                /* stime scaled on frequency etc */
  82.         __u64        cpu_scaled_run_real_total; /* scaled cpu_run_real_total */
  83. };

復(fù)制代碼


貌似和磁盤io有關(guān)的是


  3. #define TASKSTATS_HAS_IO_ACCOUNTING
  4.         /* Per-task storage I/O accounting starts */
  5.         __u64        read_bytes;                /* bytes of read I/O */
  6.         __u64        write_bytes;                /* bytes of write I/O */
  7.         __u64        cancelled_write_bytes;        /* bytes of cancelled write I/O */           這個如何理解呢???
復(fù)制代碼


cancelled_write_bytes是怎么一回事?
另外和cpu利用率有關(guān)的是哪些成員? 最后說的SMT又是什么意思呢?


要是想得到利用率的話是不是需要讀取兩次相減再除以時間間隔?還是有什么別的直接的辦法?
這里面講的task和process的區(qū)別是什么呢? task帶表進(jìn)程組 process帶表進(jìn)程?
另外再請問有沒有除proc外的其他接口直接獲得所有進(jìn)程號的呢?


問了好多問題,希望大家不吝賜教
謝謝!


http://kernelnewbies.org/Linux_2 ... ed22c281ca9ab54bb12

IO Accounting

The present per-task IO accounting isn't very useful. It simply counts the number of bytes passed into read() and write(). So if a process reads 1MB from an already-cached file, it is accused of having performed 1MB of I/O, which is 'wrong'. So this IO accounting implements per-process statistics of "storage I/O" (i.e.: I/O that _really_ does I/O on the storage device - Linux already had I/O storage statistics but it's not per-task). The data is reported through taskstats and procfs (/proc/$PID/io) (commit 1, 2, 3, 4, 5, 6, 7, 8, 10, 11)

最后一句話說的proc/$id/io是說的新的io accountting還是前面說的present per-task IO accounting ?
如果是新的的話就可以直接讀proc下的pid下的io了,比netlink更方便, 不知道效率上是不是會比netlink差
作者: Godbach    時間: 2008-12-17 09:49
如果單說讀出進(jìn)程CPU的利用率，應(yīng)該ps就可以實(shí)現(xiàn)吧。
作者: dajun    時間: 2008-12-17 09:53
還有磁盤io,不想用shell實(shí)現(xiàn)



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