Changes between Initial Version and Version 1 of jazz/08-08-26

Timestamp:

Aug 26, 2008, 7:23:12 PM (17 years ago)

Author:

jazz

Comment:

--

jazz/08-08-26

@@ +1 @@
+
+ * /usr/src/linux/Documentation/iostats.txt
+{{{
+On 2.4 you might execute "grep 'hda ' /proc/partitions". On 2.6, you have
+a choice of "cat /sys/block/hda/stat" or "grep 'hda ' /proc/diskstats".
+}}}
+{{{
+2.6 diskstats:
+   3    0   hda 446216 784926 9550688 4382310 424847 312726 5922052 19310380 0 3376340 23705160
+
+Field  1 -- # of reads issued
+    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 request_queue_t and decremented as they finish.
+Field 10 -- # of milliseconds spent doing I/Os
+    This field is 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.
+
+   3    1   hda1 35486 38030 38030 38030
+
+Field  1 -- # of reads issued
+    This is the total number of reads issued to this partition.
+Field  2 -- # of sectors read
+    This is the total number of sectors requested to be read from this
+    partition.
+Field  3 -- # of writes issued
+    This is the total number of writes issued to this partition.
+Field  4 -- # of sectors written
+    This is the total number of sectors requested to be written to
+    this partition.
+
+}}}