Extremely sluggish system with newest kernels under high memory load
When using newest kernels (starting with 3.0 till 3.2), system becomes unresponsive when some application fills up all (or almost all) physical memory. One way to reproduce - importing some complicated multipage pdf document in Gimp. When ram usage hits about ~900mb (1G ram total), computer basically locks up - takes more than 10 seconds to respond to single keypress. Also high HDD activity is observed. Of course it's logical - I guess kernel tries to move something to swap partition. The thing is, even after longer waiting, HDD trashing is still going on and swap usage almost hasn't changed. When using kernel 2.6.39, system gets somewhat sluggish in this scenario, but at least completely managable, and I can see swap usage climbing. I have tried to fiddle with some virtual memory parameters (like swappiness), but nothing helped. This problem was even worse in 3.0 kernels - I got some serious sound stuttering during even relatively light I/O - like launching video player. All tested kernels are self-compiled. Any clues are more than welcome, since this bug (or "feature") is very annoying (especially when this happens during some network gaming session).