On Mon, Sep 13, 2021 at 8:51 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > On Mon, 2021-09-13 at 11:13 -0400, Jeff Layton wrote: > > On Mon, 2021-09-13 at 18:43 +0530, Venky Shankar wrote: > > > 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 > > > > > > The math involved in keeping track of the average latency and stdev > > > seems incorrect, so, this series fixes that up too (closely mimics > > > how its done in userspace with some restrictions obviously) as per:: > > > > > > NEW_AVG = OLD_AVG + ((latency - OLD_AVG) / total_ops) > > > NEW_STDEV = SQRT(((OLD_STDEV + (latency - OLD_AVG)*(latency - NEW_AVG)) / (total_ops - 1))) > > > > > > Note that the cumulative latencies are still forwarded to the MDS but > > > the tool (cephfs-top) ignores it altogether. > > > > > > Venky Shankar (4): > > > ceph: use "struct ceph_timespec" for r/w/m latencies > > > ceph: track average/stdev r/w/m latency > > > ceph: include average/stddev r/w/m latency in mds metrics > > > ceph: use tracked average r/w/m latencies to display metrics in > > > debugfs > > > > > > fs/ceph/debugfs.c | 12 +++---- > > > fs/ceph/metric.c | 81 +++++++++++++++++++++++++---------------------- > > > fs/ceph/metric.h | 64 +++++++++++++++++++++++-------------- > > > 3 files changed, 90 insertions(+), 67 deletions(-) > > > > > > > This looks reasonably sane. I'll plan to go ahead and pull this into the > > testing kernels and do some testing with them. If anyone has objections > > (Xiubo?) let me know and I can take them out. > > > > Thanks, > > Hmm...I take it back. There are some non-trivial merge conflicts in this > series vs. the current testing branch. Venky can you rebase this onto > the ceph-client/testing branch and resubmit? Sure, will do. > > Thanks, > -- > Jeff Layton <jlayton@xxxxxxxxxx> > -- Cheers, Venky
