Hi Kairui, > Just like we already have a "swappiness=" parameter in the reclaim > interface, perhaps adding a "swap.tier=" would be better and much > cleaner to achieve the same goal? Based on Youngjun's work here: > https://lore.kernel.org/all/[email protected]/
Thanks, I think that's the right base. I tried it: on top of Youngjun's v11, a "swap.tier=" argument to memory.reclaim is about 40 lines. In a VM with zram at a higher priority than a disk swap device, and a cgroup whose tier mask allowed only the disk, ordinary reclaim in that cgroup stayed on the disk, while memory.reclaim with "swap.tier=" pointing at zram went to zram only. What it doesn't cover yet is reclaim outside any configured cgroup: under global pressure, a cgroup nobody configured still reached the zram tier. So for v3 I'd like to add a system-wide limit on which tiers pressure reclaim may use, on top of the per-cgroup settings. I'll wait for Youngjun's v12 and build on that. Thanks, Matthias
