On Freitag, 3. August 2007, Richard Freeman wrote: > Volker Armin Hemmann wrote: > > emm, from my very personal point of view: no > > > > swap is horrible slow. Its use must be avoided at any cost. Swap sucks. > > Everything is faster than accessing swap. So hitting the disk to read or > > write some files is IMHO better than hitting the disk to shove X into > > swap. > > > > X in swap is another problem. You can be sure, if X is forced into swap, > > because gcc uses up all ram for itself, everything sucks. Mouse is jerky, > > windows need ages to get displayed. > > Depends - if you're not using X then you won't mind X getting swapped > (running emerge from ssh/etc). If you are using X then chance are it > won't get swapped in the first place. If the issue is gcc using all ram > for itself, then the presence/absence of tmpfs probably won't make much > difference - gcc still has to run. > > I don't see why swap should be any better/worse than any other form of > disk access. If anything it is superior as it allows the kernel to > manage it like any other form of RAM, and the kernel isn't forced to > flush it out to disk within some time (writes to a filesystem are forced > to sync within some time to prevent data loss - this hurts performance > and is totally unnecessary for temporary build files that will get > deleted when you re-run emerge anyway).
where is the difference between 'app syncs its files to disk' and 'kernel swaps app to disk, than decides to swap it in, so app can decides which files it wants to sync to disk, then swap it out again'? oh, more disk access... > > Now, if somebody has empirical data I'll certainly pay attention, or at > least a lot of expertise. However, I wouldn't jump to the conclusion > that swap is worse than ordinary disk writes - linux manages swap fairly > well all things considered. If you don't like how it is being managed > there are kernel settings that can be used to tweak it (swappiness, etc). swappiness just prevents the kernel from swapping, when their is enough ram left. It does not improve the speed of swap. And honestly? From my 'feelings' swap is way slower than normal disk accesses. -- [EMAIL PROTECTED] mailing list
