systemd-oomd issues on desktop

[Steve Langasek]

On Thu, Jun 09, 2022 at 01:00:45PM -0400, Nick Rosbrook wrote:
> In the reports I refer to above, applications are being killed due to
> (1). In practice, the SwapUsedLimit might be too easy to reach on
> Ubuntu, largely because Ubuntu provides just 1GB of swap. Since we
> follow the suggestion of setting ManagedOOMSwap=kill on the root slice
> [7], every cgroup is eligible for swap kill. When this condition is
> met, user applications like browsers are going to be killed first.

In terms of behavior that we want to see, this last sentence sets off red
flags for me.  There are times when, due to memory pressure, killing
processes to reclaim memory is the right answer; and it is likely that the
process using the most memory on a desktop system is the browser.  But in
terms of how a modern desktop is used, it's also quite likely that the
browser is the most important process to the user experience on a desktop. 
(Cf. the Chromebook experience, where the browser effectively *is* the
desktop.)

I understand how we've arrived at the situation that browsers are the
processes likely to be killed first when there's memory pressure; but
separately from the question of what we should do for systemd-oomd overall,
are there configuration changes we could make to lower the priority of the
browser as a candidate for oom killing, and would those be reasonable
configuration changes to make?

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                   https://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org
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