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Is Swap Necessary?
johnnyb writes "Kernel Trap has a great conversation on swap, whether it's necessary, why swapless systems might seem faster, and an overall discussion of swap issues in modern computing. This is often an issue for system administrators, and this is a great set of posts about the issue."
All the docs on Linux and swap amounts to use are from the days of 386s and 4 megs of ram!
I want to know how much swap I should REALLY be using for a system with 1 gig of ram.
Same for some of the kernel compilation docs. Maybe on a 4 meg system compiling that extra option might cause slowness but on a 500 meg system does an extra 30k in the kernel matter?
Can we get some docs that aren't from the mid 90s!
I've built many servers, embedded systems, and even desktop systems that don't use any swap at all. Many more I limit the amount of swap greatly. The overall responsiveness is much better if you don't use swap and I find system stability to be better. Really it doesn't matter what the systems are used for or how many apps are being ran.. it's just how much memory you're going to use compared to the amount of physical memory you can afford. You can run out of memory just as easily using swap as you can while limited to physical memory.. the main difference being that the recovery of the sitution is much worse in the case of using swap. Quite often the system starts to churn and then grinds to a halt. Without swap those tasks just die and everything else keeps running. Setting memory limits on tasks is a good way of ensuring which tasks are killed first but I'd like to see better control of this given to the admin.
At what price learning? At what cost wisdom? The price is a man's peace of mind, and the cost is his life.
Surely if your system runs out of RAM it shouldn't die? The runaway process, sure, but the OS should be able to reclaim some RAM from that and manage to carry on, no?