[PATCH v2 0/4] ceph: forward average read/write/metadata latency

[Venky Shankar <vshankar@redhat.com>]

v2
  - rename to_ceph_timespec() to ktime_to_ceph_timespec()
  - use ceph_encode_timespec64() helper

Jeff,

To apply these, please drop commit range f4bf256..840d9f0 from testing branch.

Right now, cumulative read/write/metadata latencies are tracked
and are periodically forwarded to the MDS. These meterics are not
particularly useful. A much more useful metric is the average latency
and standard deviation (stdev) which is what this series of patches
aims to do.

The userspace (libcephfs+tool) changes are here::

          https://github.com/ceph/ceph/pull/41397

Note that the cumulative latencies are still forwarded to the MDS but
the tool (cephfs-top) ignores it altogether.

Latency standard deviation is calculated in `cephfs-top` tool.

Venky Shankar (4):
  ceph: use ktime_to_timespec64() rather than jiffies_to_timespec64()
  ceph: track average r/w/m latency
  ceph: include average/stdev r/w/m latency in mds metrics
  ceph: use tracked average r/w/m latencies to display metrics in
    debugfs

 fs/ceph/debugfs.c |  5 ++--
 fs/ceph/metric.c  | 63 +++++++++++++++++++++++++++--------------------
 fs/ceph/metric.h  | 63 ++++++++++++++++++++++++++++++-----------------
 3 files changed, 79 insertions(+), 52 deletions(-)

-- 
2.31.1