On Wed, Nov 22, 2023 at 7:01 AM Chris Li <chrisl@xxxxxxxxxx> wrote: > > On Tue, Nov 21, 2023 at 5:19 PM Nhat Pham <nphamcs@xxxxxxxxx> wrote: > > > > "all": zswap + swapfile > > > "zswap": zswap only > > > "no_zswap": swapfile only. > > > "none": no swap. > > > > > > All keyword names are open to suggestions. > > > > SGTM! There might be some functionality duplication between > > memory.swap.tiers = no_zswap and memory.zswap.max = 0, but > > otherwise this seems reasonable to me. > > > > no_zswap sounds a bit awkward, but I can't come up with a better > > name. > > I sleep on it a bit. I should apply my own suggestion of using the > positive words rather than negative one to myself. > I actually define it as a non RAM base swap device. How about "disk"? > It will include SSD and HDD disk. > > The current 4 combination will be: > > "all": zswap + disk swap file > "zswap": zswap only > "disk": disk only (including SSD and HDD) > "none": no swap for you. > > Chris Hi Chris, I chatted with Johannes a bit more about this design. While we still think it's potentially useful for the future, it lacks a concrete use case at the moment. We don't even have the infrastructure for multiple swap tiers at the moment, so adding this interface now is just making it more confusing for the users. I think zswap.writeback is a much more specific interface, with concrete and immediate usability (it stems from internal chatters and requests - so the demand is already there). I think we should just land the change we currently have (rebased on top of mm-unstable to resolve merge conflicts etc.). I don't think zswap.writeback will get in the way of any swap.tiers functionality, correct? There might be some functionality duplication, but that's not too bad IHMO. Then we can work on swap.tiers design and implementation as we add the support for multiple swap tiers.
