JonasMar 6

One thing I obsess a little bit over is the fact that it’s 2026, we pretend that Linux is a serious OS, but we‘re still losing your data on a regular basis.

Out of memory conditions (OOM) are one of our biggest pain points, so I just did a quick experiment with macOS to see how they are handling OOM.

I loaded about 200 memory heavy tabs in Firefox and kept a close look at memory usage.

(1/4)

Show threadroot42Mar 6
@verdre you can disable memory overcommitment I think? Never tried that, as I rarely have issues with OOM. But it should give processes an error when they try to malloc, which they then could handle.
Show threadZack WeinbergMar 6

@root42 @verdre I have not tested this thoroughly, but I believe that a hefty chunk of Linux's problems with swap thrashing are, at root, caused by its default heuristic that allows 20% of RAM to fill up with data that needs to get written to disk, before it actually starts making write() wait for the disk.

20% of RAM nowadays can easily be in the gigabytes. It takes at least a few seconds to flush all of that to even the fastest SSDs. But it takes only milliseconds to fill it up.

Show threadZack WeinbergMar 6

@root42 @verdre Swap thrashing went away forever for me when I started using these sysctl settings:

vm.overcommit_memory = 2
vm.overcommit_ratio = 95
vm.dirty_background_bytes = 16777216
vm.dirty_background_ratio = 0
vm.dirty_bytes = 67108864
vm.dirty_ratio = 0

which means no overcommit, reserve 5% of swap for root, start background writeback at 16 *megabytes* of dirty data and throttle writers at 64 megs

I'd love to work with someone on a proper study of whether this makes sense for everyone

Show threadjon rMar 7
@zwol
This sounds like proper Phoronix material.
@root42 @verdre
Show threadZack Weinberg
@yala @root42 @verdre Uh. It has been my impression for many years that Phoronix is in the business of farming ad impressions, and doesn't publish anything worth reading. Is that inaccurate?
Mar 7 at 6:45pmWeb
Show threadjon rMar 7
@zwol
I can't tell, I'm using an ad blocker. But they get a lot of hardware sent for free for testing, if that is of concern. But I like the overview on happenings in Linux land. I'm not so much into lwm.net and such.
At least Phoronix does extensive hardware testing and is focussed on Linux, not like many other publications, such as Tom's Hardware or so.
@root42 @verdre