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Post by Matt Blaze

Earlier in the thread

Hanno Zulla @hzulla@infosec.exchange

This is FASCINATING. Researchers were able to pin down the cause of measurable global 60 second power spikes to software that does regular checks on the minute mark. They found large scale battery installations as one major cause, but obviously this is true for any other computerized system that does cron jobs and has a synchronized clock. As weird as it sounds, adding random 0-59.999s delays to cron jobs in Linux distributions and other software would actually help the power grid.

fz-juelich.de/en/news/archive/

Mystery of 60-Second Fluctuations in Power Grids Solved Why do our grids show a brief spike in electricity demand every minute? A team led by Dirk Witthaut from Forschungszentrum Jülich has now demonstrated that this is due to regular power checks carried out by large-scale battery storage systems. These findings could help to make our electricity supply more robust, as the team reports in an article published in Nature Energy.

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Hanno Zulla @hzulla@infosec.exchange

It is such an obvious cause once you think about it, and yet before you hear about this, no software developer or maintainer ever considers the possible effects of e.g. a default Debian cron job setting may have on the global electricity grid.

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Matt Blaze @mattblaze@federate.social

@hzulla Cron, of course, dates back to a world in which:

- computers were a significantly smaller part of the load on the power grid
- we didn't have tightly synchronized clocks everywhere (no NTP yet)
- we didn't have architectures in which power consumption was as tightly linked to computational load

Software often outlives all sorts of assumptions!

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Replies

Christian Berger DECT 2763 @casandro@f-ckendehoelle.de

@mattblaze @hzulla Which Cron? I mean there are, for good reasons, many different versions of Cron out there. There are Crons that target specific use cases the original writers didn't consider (like having computers that are turned off or in standby from time to time).

That's the wonderful thing about Free Software. It's not a "product" but instead a chorus of competing ideas and forks which explore new things.

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Matt Blaze @mattblaze@federate.social

@casandro @hzulla Um, if open source or free software or whatever buzzword the kids are calling it these days solves this problem, why wasn’t it solved already? As you pointed out, cron’s code has been re-implemented many times over the years.

Open source is nice and all, but it didn’t anticipate or solve this.

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Philip Bragg @synx508@bsd.network

@mattblaze @casandro @hzulla This isn't really a problem that requires changes in the software but rather changes in the way it's used. There is no escaping the necessity of *some* tasks being scheduled at the exact times provided by the various crons. I used to run a fairly big website on meagre hardware and had to dither a lot of scripts to spread CPU load out, this included cron jobs. This also smoothes the power draw.

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Matt Blaze @mattblaze@federate.social

@synx508 @casandro @hzulla yes, exactly. The software changes required to have cron behave in a way that’s more friendly to the power grid are relatively trivial here. The issue is (apparently) that no one realized (or cared) that synchronized surges in computation can now have a measurable impact at scale (which is an interesting effect).

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