Messages in this thread | | | Date | Sat, 19 Dec 1998 13:45:23 +0100 (CET) | From | Rik van Riel <> | Subject | Re: swap cache |
| |
On Sat, 19 Dec 1998, Prasun Kapoor wrote:
> > Linux VM, but we don't need that functionality: in Linux we have always > > swapped out ptes on a per-page-table basis, not on a per-physical-page > > basis. We *DO* swap processes out independently. > > I dont think I understand. The whole idea of doing it globally is > to do some kind of LRU on a global scale and swap out pages based > on that.
This terribly fragments swap space -- you seem to be forgetting that we also need to swap things back _in_ and that is most efficient when the process' pages are contiguous on disk.
LRU is just a good guess, the method Linux uses might be a bit worse on swap-out, but since we do less disk _seek_ I/O we come out slightly ahead of the normal way...
For Linux 2.3 we are planning several major enhancements to this scheme though (much better I/O clustering and swap read- ahead/behind and several other goodies).
cheers,
Rik -- the flu hits, the flu hits, the flu hits -- MORE +-------------------------------------------------------------------+ | Linux memory management tour guide. H.H.vanRiel@phys.uu.nl | | Scouting Vries cubscout leader. http://www.phys.uu.nl/~riel/ | +-------------------------------------------------------------------+
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |