Re: An idea for prefetching swapped memory...

[Christophe Saout <christophe@saout.de>]

Am Mon, 2003-04-07 um 12.21 schrieb Con Kolivas:

> > With this feature there should be no performance decrease because only free
> > resources would be used, and if pages were swapped in but not be used, they
> > stay not dirty and so have not to be written to disk when they are swapped
> > out again. But the improvements should be obvious if simply the last swaped
> > out pages are swapped in again...
> 
> This has been argued before. Why would the last swapped out pages be the best 
> to swap in? The vm subsystem has (somehow) decided they're the least likely 
> to be used again so why swap them in?

Are you sure this is working? When I'm watching a video ofer NFS on my
machine which is idle (just X and mplayer, gnome in background, 256 MB
of memory, 512 swap), after 30 minutes or so, the playback starts to
jump. The cpu usage is below 10%, and it even does this when both X and
mplayer are renice to -19 (!). So the VM swapped everything out and
after 30 minutes it starts to swap out X oder mplayer itself, which is
immediately swapped back in but the video jumps... :-(

-- 
Christophe Saout <christophe@saout.de>