Any userspace process can see how low the memory is though, firefox could do it itself.
Still, if a notification system is already used in other OSes, a very easy solution would be to add such notification channel in userspace so that any process could ask firefox to free memory.
Right now I am using earlyoom to save my system from freezing. It sometimes kills firefox, sometimes dbeaver, sometims VMs. But if it could tell firefox to chill for a bit and free memory, then I could avoid the massacre (at least sometimes).
> Any userspace process can see how low the memory is though
How, exactly?
Or put another way, how do you reliably tell apart "we are seriously thrashing" and "resident memory is getting close to the physical memory limits but there is plenty of totally cold stuff to swap out and it won't be a problem" from userspace? The kernel is the only thing that can make that determination somewhat reliably.
Maybe there's a better way than this, but the same way earlyoom decides it's time to kill processes (% RAM usage) firefox would decide it's time to free cache. While using the 100% of RAM might be the optimal state if you aren't going to use more than that, it's not safe.
