smarks

I don't know, but I did observe differences in power consumption caused by all sorts of unexpected things.

At some point during all my fiddling with this stuff, I discovered a correlation between GPU power consumption (as indicated by iStat Menus) and fan speed. For example, if I switched to high resolution, the power would increase, and at low resolution, power would decrease. And of course more power means more heat, which causes the fans to run. That kind of made sense: moving more pixels consumes more power.

But I also observed an effect caused by refresh rate. Oddly, I seem to recall 30Hz would cause increased power draw but 60Hz the power draw was reduced. Yes, this seems counterintuitive. Since I didn't have a good model for what caused the increased power draw, I decided to try all combinations of the settings. On a lark I tried inverting the image and it actually affected the power draw! Probably has something to do with the access order of memory, but I don't really know. And indeed it seems odd that running the image upside down actually pulled less power than right side up.

The cabling issue was a bit more complicated. My initial configuration was to run the video through a dock, with the dock's video output going to the monitor. That always resulted in high power draw. Connecting the computer directly to the monitor did have the effect of reducing power draw... but only in certain configurations.

Oh yeah, I forgot about the graphics.

I had (and still have) a 4k external monitor. Naturally I wanted the MBP to drive the monitor with a resolution that took advantage of all the pixels. Unfortunately with most monitor settings the GPU power consumption would produce enough heat to run the fans even if the rest of the system was completely idle! If I set the output to full HD the GPU would cool down and the fans would turn off. But full HD on a 4k monitor is a waste.

It was very strange. I could drive the monitor at 4k but with the image upside down, and the power consumption would be low. But flip the image right side up and it would run hot and turn on the fans.

It took a couple weeks of fiddling, but I finally found a combination of refresh rate, resolution, image orientation (right side up!), and cabling that let me drive the monitor at high resolution without running the fans. What a pain.

(I used iStat menus to monitor GPU power consumption. At “good” settings it consumed about 5w. At “bad” settings it would consume 17w. At a bad setting you could immediately see the various temperatures go up and the fans spinning up to compensate.)

Warming up a 2019-era (Intel) MacBook Pro was never my problem. Quite the opposite. Those machines ran notoriously hot. The later macOS releases, combined with company-mandated crapware, made it worse. Doing an ordinary build or starting a videoconferencing session was enough to cause the fans to run. On a warm day the fans couldn’t shed enough heat and so the system would go into thermal throttling. The OS would occupy a core with a 100% kernel_task that didn’t do any work but which would serve to prevent actual work from being scheduled onto that core. When four or five out of the six cores were occupied by kernel_task, I knew I was in for a bag of hurt (to steal a phrase from Steve Jobs). Responsiveness went completely to hell. The machine became effectively unusable.

After a while my normal procedure was to run with the thing sitting on top of an ice pack. That would let me run a 60-90 minute video conference without troubles.

The only redeeming feature of these machines is that they could emulate old x86 hardware at speed. That allowed me to run old apps on old OSes without having to keep old hardware running.

I took another look at L.H.S. and the buildings have rather more octagons than hexagons. There’s even a decagon-shaped building. Still, the symmetric geometry of the architecture is quite striking.

Thanks for your explanation; it’s very helpful.

Part 2 shows this comment from the Linux TCP code:

    /* As outlined in RFC 2525, section 2.17, we send a RST here because
     * data was lost. To witness the awful effects of the old behavior of
     * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk
     * GET in an FTP client, suspend the process, wait for the client to
     * advertise a zero window, then kill -9 the FTP client, wheee...
     * Note: timeout is always zero in such a case.
     */

Ok, so the RST is explained and well justified by the literature. But what are the “awful effects” of sending FIN instead? Can someone explain?

I rewatched this recently; I think it held up well. It’s probably re-entered the zeitgeist given the recent developments in “AI” and “agents”. So far accidents seem to have destroyed only data, but it’s only a matter of time before some fool hooks up an “AI agent” to a missile.

Much of the film was shot at the Lawrence Hall of Science in the hills above Berkeley, California. This building was probably chosen because of its unique brutalist hexagonal architecture. I spent a bunch of time there as a kid.

Eric Braeden (Forbin) is still alive, but his house in Pacific Palisades burned down in the 2025 fires. :-(

Oh! This is a great explanation, thanks. I remember your original exchange (and I found it baffling and uncharacteristic), and I remember the William Shatner SNL Trek convention sketch, but I never made the connection between them.

Thanks for posting this. The Leveson article is IMO the definitive study on this incident. I’m going to repost at top level for emphasis.

There's a meta-problem here, which doesn't seem to have been discussed. How did the setting change in the first place? The article says:

> Then, seemingly out of nowhere...

> In my case, the “Wake for maintenance” option was disabled...

So presumably the option was originally enabled. Somehow it was disabled, resulting in the battery-draining behavior. Re-enabling it manually solved the problem. Great.

But how did the setting get changed in the first place?

I've noticed this on my Macs (actually mostly the new one; not the old, obsolete ones I still run) as well as various iOS devices. At some point I'll notice some odd, unusual, or different behavior. Hunting around in the settings, I'll sometimes find an option that seems like it should control the behavior. Changing the setting has the desired effect of restoring the former behavior. So what changed it? It's a mystery.

A memorably egregious example was the "do not disturb" setting. I normally have do-not-disturb enabled from 11pm to 7am on my phone so I'm not awakened by notifications. But one night I was awakened at 3am by my phone buzzing, because some random text message had arrived. Huh?!? The next day, working on my Mac, it seemed unusually quiet... maybe a lot of people were on vacation or something. Then I checked Slack and there were a lot of messages pending, questions put to me that went unanswered, and even speculation that I had gone on vacation. What happened? My Mac had somehow set itself to do-not-disturb from 9am to 5pm, which covers most of the workday. And my iOS devices also had do-not-disturb set for the same incorrect time interval. (Well at least I got a lot of work done.)

In this case I suspect iCloud settings synching was the culprit. My conjecture is that I logged into my iCloud account from a new device, and that device's default settings got synched to my other devices. But I'm not entirely sure.

I know I've had other cases where settings seemed to be changed spontaneously. My speculation is that OS updates will change settings. Unfortunately this isn't reproducible, and it happens rarely and with different settings. But it's happened enough times over the past couple years that it seems to be a pattern. Maybe it happened to the OP. Does anybody else experience this?