re: unconfiguring swap at shutdown

[christos%zoulas.com@localhost (Christos Zoulas)]

On Aug 31,  4:59pm, mrg%eterna.com.au@localhost (matthew green) wrote:
-- Subject: re: unconfiguring swap at shutdown

|    Kernel option? Sysctl? Are you sure it is slow (and do you know
|    why it is slow)? Because at that time there are no processes left,
|    and from my experience unmounting filesystems with a lot of unwritten
|    data is a lot slower, or it appears to be.
| 
| i think sysctl.

ok.

| it's slow when you have a lot of swap in use and swapoff means bringing
| them all back into memory.  and those transfer happen at PAGE_SIZE at
| a time, which is a lot slower than 64KB at a time (which is what pageout
| can manage.)

How can you have a lot of swap in use when there are no processes left?
Or it does not matter, and swapoff means that it has to fetch each page
of swap configured? Why does it have to do this anyway?

christos