include/linux/task_io_accounting.h

   1 /*
   2  * task_io_accounting: a structure which is used for recording a single task's
   3  * IO statistics.
   4  *
   5  * Don't include this header file directly - it is designed to be dragged in via
   6  * sched.h.
   7  *
   8  * Blame akpm@osdl.org for all this.
   9  */
  10
  11 struct task_io_accounting {
  12 #ifdef CONFIG_TASK_XACCT
  13         /* bytes read */
  14         u64 rchar;
  15         /*  bytes written */
  16         u64 wchar;
  17         /* # of read syscalls */
  18         u64 syscr;
  19         /* # of write syscalls */
  20         u64 syscw;
  21 #endif /* CONFIG_TASK_XACCT */
  22
  23 #ifdef CONFIG_TASK_IO_ACCOUNTING
  24         /*
  25          * The number of bytes which this task has caused to be read from
  26          * storage.
  27          */
  28         u64 read_bytes;
  29
  30         /*
  31          * The number of bytes which this task has caused, or shall cause to be
  32          * written to disk.
  33          */
  34         u64 write_bytes;
  35
  36         /*
  37          * A task can cause "negative" IO too.  If this task truncates some
  38          * dirty pagecache, some IO which another task has been accounted for
  39          * (in its write_bytes) will not be happening.  We _could_ just
  40          * subtract that from the truncating task's write_bytes, but there is
  41          * information loss in doing that.
  42          */
  43         u64 cancelled_write_bytes;
  44 #endif /* CONFIG_TASK_IO_ACCOUNTING */
  45 };