My laptop is a thermometer for my office

Below is processor temperature by hour of day, using only readings where the machine was genuinely idle: nothing much running, screen not in use, no external monitor plugged in, and at home rather than travelling. The line is the typical value; the shaded band covers the middle 80% of readings.

It runs from 38.3°C around 08:00 up to 42.6°C around 17:00. That is a 4.3°C daily swing, and it is the house: coolest before dawn, warmest in the early evening, exactly as a building with thermal mass behaves.

Two things could fake this, and both are excluded rather than argued away. An external monitor adds several degrees on its own and gets plugged in during the day, so any reading with one attached is dropped. And a processor stays warm for a while after finishing work, so busy readings are dropped too, not merely averaged down.

What survives all that is 1,912 of 27,301 readings — 7.0%. That ratio is the whole reason this needs months of history: the useful moments are the rare ones. 4 hours of the day have too few idle readings to plot and are left as gaps — mid-morning, the machine is almost never sitting still.

Same sensor, plotted against how hard the machine is working rather than the time of day. This is the chart you'd expect: work goes up, temperature goes up, from about 40.2°C at rest to 87.2°C under sustained load.

Both configurations are drawn on one chart below. Plugging in an external monitor shifts the whole curve upward by a few degrees — the two lines are the same response at two heights.

I run a lot of coding agents. Enough that at least one is running in 95% of all readings ever taken, and it is not unusual to have half a dozen going at once. The chart below counts concurrent claude processes — one per session — taking the busiest moment of each day. The record is 22 at once, on 2026-05-17.

They are not free. Swapping — what happens when a machine runs out of real memory and starts shuffling data onto disk to cope — climbs steadily with the number of agents running, from about 10.6 GB with none to 14.0 GB with 8 or more, on a machine with 24 GB of memory installed.

The chart below tracks both over the whole run. Memory used sits pinned near the 24 GB ceiling the entire time, and swap lives high with it — peaking at 34 GB, well past the physical memory installed, because swap spills onto disk. This laptop has been over its memory budget continuously for four months. Not spiking under load — simply living there.

One way to ask whether a machine has enough memory: add up what it is actually holding — the part kept in fast RAM plus the part pushed out to disk — and compare it to the RAM installed. That total is the working set, the memory the workload genuinely wants at once.

Here it sits above the 24 GB line on 104 of 126 days. Typically it wants 29 GB, on a busy day 37 GB, and at its peak 52 GB — more than twice the RAM installed. The resident line, meanwhile, is pinned flat just under the ceiling: it can't rise to meet demand because there's no more RAM to rise into, so everything above it spills to disk. That flat line under a floating one is what a memory-constrained machine looks like.

Disk space in use, day by day, out of 1,858 GB. The underlying trend is upward at about 1.1 GB a day, which is the boring part.

The interesting part is the cliffs. The largest is 623 GB vanishing on 2026-07-08 — a working set of datasets and build artifacts that accumulated for weeks and then got cleared out in one go. A monthly average would show none of this.

Each bar is one stretch between restarts. The longest ran 92 days. If you reboot weekly this will look reckless; if you run servers it will look normal.

The first bar is an undercount — that session had already been running for some time when the recording started, so its true length is unknown.