This feature request can be broken down into 4 items:
1) Kernel changes for dm to use the existing kernel I/O stats mechanism;
2) A new kernel dm module to gather sophisticated customised stats;
3) Simple userspace tools changes to make it easy to use (2);
4) Sophisticated userspace tools (and gui) changes to get the best out of (2).
I'm going to use this bugzilla to cover 1 and 2 ('kernel' component).
Someone might like to raise new ones to cover 3 and 4 (device-mapper / lvm2 /
lvm2 GUI components).
The patch for (1) is simple - needs a review, but certainly feasible for U3.
The patch for (2) also exists but is more complex - not reviewed properly yet,
API needs more work, but might be possible to include it in some form in U3 if
*** Bug 143390 has been marked as a duplicate of this bug. ***
*** Bug 170693 has been marked as a duplicate of this bug. ***
Created attachment 121243 [details]
test cases for dm diskstat
Test cases for dm diskstat.
To complete this test, timing information collected by
BZ#173398 is also needed.
- Criteria for read_ticks, write_ticks, io_ticks may be
too strict and sometimes cause false negative.
Needs several trials to avoid it.
- There may be better/finer criterion for time_in_queue.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.