On Apr 7, 2015, at 7:44 PM, Francois Lafont wrote:
> Chris Kitzmiller wrote:
> I graph aggregate stats for `ceph --admin-daemon
>> /var/run/ceph/ceph-osd.$osdid.asok perf dump`. If the max latency strays too far
>> outside of my mean latency I know to go look for the troublemaker. My graphs
>> look something like this:
>>
>> [...]
>
> Thanks Chris for these interesting explanations.
> Sorry for my basic question but which is the entry in the output that gives
> you the read latency?
>
> Here is an example from my cluster (Firefly):
>
> ~# ceph --admin-daemon /var/run/ceph/ceph-osd.2.asok perf
>
> [...]
>
> "osd": { "opq": 0,
> "op_wip": 0,
> "op": 3566,
> "op_in_bytes": 208803635,
> "op_out_bytes": 146962506,
> "op_latency": { "avgcount": 3566,
> "sum": 100.330695000},
> "op_process_latency": { "avgcount": 3566,
> "sum": 84.702772000},
> "op_r": 471,
> "op_r_out_bytes": 146851024,
> "op_r_latency": { "avgcount": 471,
> "sum": 1.329795000},
>
> [...]
>
> Is the value of "op_r_latency" (ie 1.329ms above)?
> In this case, I don't understand the meaning of "avgcount"
> and "sum".
>
> "sum" is the sum of what?
> "avgcount" is the average of what?
There are a bunch of these avgcount/sum pairs and, from what I've gleaned, you're to simply divide sum by avgcount to get the mean of that particular stat over whatever time frame it is measuring.
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