Re: [PATCH v9 0/5] ceph: add perf metrics support

[Jeff Layton <jlayton@kernel.org>]

On Mon, 2020-03-09 at 03:37 -0400, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> Changed in V9:
> - add an r_ended field to the mds request struct and use that to calculate the metric
> - fix some commit comments
> 
> We can get the metrics from the debugfs:
> 
> $ cat /sys/kernel/debug/ceph/0c93a60d-5645-4c46-8568-4c8f63db4c7f.client4267/metrics 
> item          total       sum_lat(us)     avg_lat(us)
> -----------------------------------------------------
> read          13          417000          32076
> write         42          131205000       3123928
> metadata      104         493000          4740
> 
> item          total           miss            hit
> -------------------------------------------------
> d_lease       204             0               918
> caps          204             213             368218
> 

Thanks Xiubo! This looks good. One minor issue with the cap patch, but I
can just fix that up before merging if you're ok with my proposed
change.

Beyond this...while average latency is a good metric, it's often not
enough to help diagnose problems. I wonder if we ought to be at least
tracking min/max latency for all calls too. I wonder if there's way to
track standard deviation too? That would be really nice to have.

Cheers,
-- 
Jeff Layton <jlayton@kernel.org>