On Mon, Mar 07, 2022 at 03:50:36PM -0500, Johannes Weiner wrote: > On Sun, Mar 06, 2022 at 03:11:23PM -0800, David Rientjes wrote: > > - swappiness factor > > This I'm not sure about. > > Mostly because I'm not sure about swappiness in general. It balances > between anon and file, but both of them are aged according to the same > LRU rules. The only reason to prefer one over the other seems to be > when the cost of reloading one (refault vs swapin) isn't the same as > the other. That's usually a hardware property, which in a perfect > world we'd auto-tune inside the kernel based on observed IO > performance. Not sure why you'd want this per reclaim request. I think this could be useful for budgeting write-endurance. You may want to tune down a workload's swappiness on a per-reclaim basis in order to control how much swap-out (and therefore disk writes) its doing. Right now the only way to control this is by writing to vm.swappiness before doing the explicit reclaim which can momentarily effect other reclaim behavior on the machine.
