This is not btrfs issue, just tested that. Live cd of Ubuntu 11.04 boots on 512 machine and runs most of time with zero swap usage. On the same machine lubuntu 11.10 and xubuntu 11.10 boot up with 100+ mb of swap used, on a system without any btrfs partition.
But weird thing is that I've upgraded Xubuntu 11.04 on that same machine to Xubuntu 11.10 and swap usage is quite normal.
Currently I can't test it on a later kernel, I'll try to do it later this week.
This is not btrfs issue, just tested that. Live cd of Ubuntu 11.04 boots on 512 machine and runs most of time with zero swap usage. On the same machine lubuntu 11.10 and xubuntu 11.10 boot up with 100+ mb of swap used, on a system without any btrfs partition.
But weird thing is that I've upgraded Xubuntu 11.04 on that same machine to Xubuntu 11.10 and swap usage is quite normal.
Currently I can't test it on a later kernel, I'll try to do it later this week.