Messages in this thread | | | Date | Wed, 20 May 1998 17:21:58 +0300 (EET DST) | From | Ville Voutilainen <> | Subject | Swapping thoughts |
| |
My current configuration has 64 MB Ram and 128 MB swap. The current kernels run pretty much OK, it's just that the swapping behavior leaves a lot to desire.
I recently had a situation where I had ~40 MB buffers and the system neverheless used ~12 MB of swap. After a while, the swap usage grew although there was 'free' memory available.
IIRC, Linus said earlier that the current kernels run better if they have some swap space to use. Anyway, the current behavior presents some problems. I did some CD burning at the time, so that's why I had tons of memory in buffers. I also had X running with several netscape windows open. The fun starts when I switch to a netscape window when that particular instance is swapped out. The switch is like a crawl.. Somehow reminds me of Solaris, which is definitely not very good. This kind of situation probably could be avoided if the CD burner could tell the kernel that the files don't need to be buffered (a useful feature anyway). But in this case that would cure only the consequence of the (IMHO bad) swap behavior, not the problem itself.
I remember the early days when a friend of mine praised the advantage of a dynamic buffer cache, saying that 'all so called free memory acts as cache and whenever an application needs more memory, the cache is shrinked.' I just would like to have that behavior back. The unneeded swapping causes bad task switch behavior and also possibly jeopardizes a CD burn or any other io-bound application since there is more disk activity, some of which could be avoided. Granted, shrinking the buffer cache might also cause more disk activity, but I don't believe it is reasonable to put so much weight on buffering versus swapping sleeping processes out, since it feels ridiculous to swap 20 MB if there are 45 MB of buffers.
Just my 0.02.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu
| |