> In my experience, a misbehaving linux system that's out of RAM and has swap to spare will be unusably slow.
Yeah, this is basically the main drawback of swap. I tried to address this somewhat in the article and the conclusion:
> Swap can make a system slower to OOM kill, since it provides another, slower source of memory to thrash on in out of memory situations – the OOM killer is only used by the kernel as a last resort, after things have already become monumentally screwed. The solutions here depend on your system:
> - You can opportunistically change the system workload depending on cgroup-local or global memory pressure. This prevents getting into these situations in the first place, but solid memory pressure metrics are lacking throughout the history of Unix. Hopefully this should be better soon with the addition of refault detection.
> - You can bias reclaiming (and thus swapping) away from certain processes per-cgroup using memory.low, allowing you to protect critical daemons without disabling swap entirely.
Have a go setting a reasonable memory.low on applications that require low latency/high responsiveness and seeing what the results are -- in this case, that's probably Xorg, your WM, and dbus.
Yeah, this is basically the main drawback of swap. I tried to address this somewhat in the article and the conclusion:
> Swap can make a system slower to OOM kill, since it provides another, slower source of memory to thrash on in out of memory situations – the OOM killer is only used by the kernel as a last resort, after things have already become monumentally screwed. The solutions here depend on your system:
> - You can opportunistically change the system workload depending on cgroup-local or global memory pressure. This prevents getting into these situations in the first place, but solid memory pressure metrics are lacking throughout the history of Unix. Hopefully this should be better soon with the addition of refault detection.
> - You can bias reclaiming (and thus swapping) away from certain processes per-cgroup using memory.low, allowing you to protect critical daemons without disabling swap entirely.
Have a go setting a reasonable memory.low on applications that require low latency/high responsiveness and seeing what the results are -- in this case, that's probably Xorg, your WM, and dbus.