What the numbers do not say
Every measurement on this site was taken on one device, on one day, under one load. This page is the list of things it therefore does not tell you — kept here, in the documentation, rather than left for a reader to discover by being wrong.
What /metrics can recover, and what it cannot
Section titled “What /metrics can recover, and what it cannot”The histogram mikroscope_ (integer busy ticks per sample and core, which keeps
timing jitter out of the bucket choice) recovers time above a threshold to one sample. It cannot recover contiguity: a 2 s plateau at 30 % and twenty
scattered 100 ms spikes at 30 % look identical in it.
That is what mikroscope_ is for —
the length of each run of consecutive samples at or above the threshold,
observed when the run ends, with the run still in progress in
…_run_open_seconds.
The trailing-window gauges (window="1s"|"10s"|"60s", stat="max"|"min"|"p95")
show the peak whatever your scrape interval is, because the agent computes them
over its own clock rather than over yours. To see the shape of a transient
rather than its envelope, record it, or let a trigger capture it.
The sampler’s own smear is published, not hidden
Section titled “The sampler’s own smear is published, not hidden”How late the sampler woke after its ticker and how long the read took are
mikroscope_ and mikroscope_, with
the interval actually achieved in mikroscope_. If you
suspect the sampler rather than the router, those three are where to look
first.
Gaps are reported, never papered over
Section titled “Gaps are reported, never papered over”The agent keeps 300 s by default. A collector outage shorter than that is
backfilled on reconnect through since=<seq>; a longer one is reported as a gap
of known length — a marker in a recording, a counter on the collector. A chart
with a hole in it is a chart telling the truth.