On Mon, 31 Dec 2012, Trent W. Buck wrote: > Anthony Hogan <[email protected]> > writes: > > > Hrrmm.. interesting RE swap. My reading in the past regarding swap > > seems to be not to starve the machine on it or stuff just dies rather > > than slows down.. it's something to keep in mind though. > > IME as at 2.6, the last time I ran with swap, "slows down" means "slows > down to the point where you can't get a shell to spawn pkill" such that > you end up having to hard reset the entire machine. Compared to that, > letting the OOM killer take a guess (and probably kill off the browser > that's causing swap thrash) seems like a good bet. YMMV &c. > > Oh, for servers I do generally still give them swap, but since they are > massively overspecced with RAM, I've never seen them actually page > anything out.
Since SSDs can almost be written to all day every day for about 5 years without developing dodgy cells these days, I decided to enable swap on my SSD based machine. And was surprised to still only get about 3MB/S swap rates (15MB/s if I also enable zram). There is something really fscking screwy in Linux's swap implementation if the best it can do when trying to swap a 1GB browser image back in from disk is 3MB/s (@ about 300 iops) off a device that can do 80,000 iops and 300GB/s read. It's been like that since at least the 2.4 days. I've only *ever* gotten 3MB/s out of the si and so columns in vmstat. (at least SSD allows me to keep using the machine for other tasks when it's busy swapping in opera). -- Tim Connors _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
