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 #ifdef CONFIG_TASK_IO_ACCOUNTING
  12 struct task_io_accounting {
  13         /*
  14          * The number of bytes which this task has caused to be read from
  15          * storage.
  16          */
  17         u64 read_bytes;
  18
  19         /*
  20          * The number of bytes which this task has caused, or shall cause to be
  21          * written to disk.
  22          */
  23         u64 write_bytes;
  24
  25         /*
  26          * A task can cause "negative" IO too.  If this task truncates some
  27          * dirty pagecache, some IO which another task has been accounted for
  28          * (in its write_bytes) will not be happening.  We _could_ just
  29          * subtract that from the truncating task's write_bytes, but there is
  30          * information loss in doing that.
  31          */
  32         u64 cancelled_write_bytes;
  33 };
  34 #else
  35 struct task_io_accounting {
  36 };
  37 #endif