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Comment by gorgoiler | Hacker News Reader

[Edit: modern debian images have “force-unsafe-io” turned on in /etc/dpkg/ so eatmydata shouldn’t make a difference.]

I’m not the OP, but in an example I just tried it took build-essential from 48s to 39s (timed on the third step, without and then with the call to eatmydata):

  from debian:sid
  run apt update && env DEBIAN_FRONTEND=noninteractive apt-get install --yes eatmydata
  run apt update && eatmydata env DEBIAN_FRONTEND=noninteractive apt-get install --yes build-essential

Can you replicate something faster? Was I doing something wrong?

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Yes, the second invocation will have hot caches. Basically the standard is to either test in a clean environment (e.g. immediately after a reboot) or to run the command until the times stabilize, and then take, say, the middle 3 out of 5 measurements.

What is cached though? DNS? IP routes to the Debian mirrors?

I ran it three more times. Plain install was 50s 48s 47s; eatmydata was 46s 46s 46s.

Installing build-essential probably does enough non-dpkg IO to account for the difference (install scripts etc, for example when libc changes and the system scans for running daemons) but it isn’t much and the delta may well be statistically insignificant.

File system. Drives cache recently read blocks. This isn’t something that’s neesesarily e en visible to the OS.

I decided to benchmark these scenarios out of curiosity, because I hadn't heard of eatmydata before or of force-unsafe-io.

- Docker image: `debian:stable-slim`

- `docker system prune -a` ran before each test.

- Packages installed: `build-essential ca-certificates libssl-dev software-properties-common wget curl git`

Results:

Default Debian settings: 48.32 seconds

force-unsafe-io enabled: 55.86 seconds

eatMyData enabled: 35.04 seconds

It's possible that the last time I dealt with that on debian force-unsafe-io wasn't set in /etc/dpkg.

I haven't really built debian-based containers in last two years.

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