default swap allocation makes system unresponsive

[Andreas Kostyrka]

On my system with 8GB RAM, the automatic created swap size if 4GB. On a typical hdd setup, filling this 4GB swap can take over an hour. During this time, the system is very unresponsive, till the out-of-memory killer can clean up the issue.

Please consider that swap has a tendency to be accessed via random patterns, and not sequentially, hence no matter how fast the hdd, there is basically a limited number of "transactions" available, hence an acceptable duration of trashing is not linear to the RAM size in any way.

All of this applies only to hdd based swap, any random-access storage (SSD, flash) has this problem not (mostly, if the IO bandwidth is to slow, an overly huge swap can again become problematic)

So to give the user a much improved experience, Ubuntu needs to limit hdd swap size, and consider using compcache sized relatively to the RAM size. I personally cannot recommend the right size (it certainly depends a little bit on the hdd, and the overall system, as I've been using compcache and SSD-based swap exclusively the last years. On LVM one can get rid of the swap partition easily enough, but without LVM it would leave me with an useless 4GB partition lying around).

Thanks