按优先级的 swap 分层 · v11

Introduce the “swap tier” as an abstraction over swap devices, so that swap allocation is organized on a tier basis rather than on a flat list of devices. Swap priority already points this way. Devic

The slow allocation path walks swap_avail_head, one plist of every available swap device, ordered by priority. Give each tier its own list of available devices instead. The slow path now walks the ti

Swap tiers do nothing until something chooses between them. Let a memory cgroup do that. Each cgroup carries a mask of the tiers it may swap to. Write a cgroup path and a hex mask to /sys/kernel/debu

Apply the cgroup tier mask during swap slot allocation to enforce per-cgroup swap tier restrictions. The folio’s mask is looked up once and passed to the fast, slow and discard paths as a parameter,