Debian's /tmpest in a teapot

Posted Jun 4, 2024 12:04 UTC (Tue) by malmedal (subscriber, #56172)
In reply to: Debian's /tmpest in a teapot by intelfx
Parent article: Debian's /tmpest in a teapot

> > Anyway let's not forget that the advice online has been "do not create swap" for decades

> That's just crappy advice.

It's obsolete advice, a 7200 RPM desktop drive can do something like 72 seeks per second. I had plenty of workloads that would work fine without swap(or at least be OOM-killed), but completely hang the machine when swap was enabled.

With an SSD-drive the problem went away so it's reasonable to enable swap again.

Debian's /tmpest in a teapot

Posted Jun 4, 2024 12:06 UTC (Tue) by intelfx (subscriber, #130118) [Link] (1 responses)

> I had plenty of workloads that would work fine without swap(or at least be OOM-killed), but completely hang the machine when swap was enabled.

I'd hazard a guess and say this just meant `vm.swappiness` had been set to a wrong value.

Debian's /tmpest in a teapot

Posted Jun 4, 2024 15:23 UTC (Tue) by malmedal (subscriber, #56172) [Link]

I did some experiments at the time, with real and synthetic workloads, only thing that worked was reducing swap-size.

The disk at the time could read 150M/sec sequentially, but only 288K/sec with random access 4K blocks. Typical for a 7200RPM desktop-drive.

The performance cliff when swap was just a little bit too large was so tall that I just turned it off.