Hi all, I've been trying to search for some mechanism(s) to reclaim resident memory of some frozen applications on a small embedded device. The typical use case is to bring up an app and once backgrounded/dismissed the idea is to freeze/thaw for faster resume/restart times. The issue is that after starting/pausing several of these applications (and subsequently freezing) memory begins dropping, and memory thrashing begins. (I can stop the apps of course, but then that leads to longer load times). I've already got memory constraint issues, which led to adding a swap partition. I've tried bumping the memory.swapiness to 100 within a memory cgroup, and waiting a few seconds for kswapd to kick in before freezing but since the app is running it only puts a handful of pages into swap. Some projects exist (crypopid(2) / CRIU) for dumping the process state in userspace, but unless I'm missing something, I'd imagine there must be some existing kernel mechanism (seems like a useful feature for small memory constrained devices) within the freezer/memory cgroups that can force all pages of the frozen process to a swap partition, and restore on thaw. Does this sort of cgroup-level S4 (hibernate-to-disk) exist or even just a mechanism to force a frozen process's pages to swap? Thanks, Tyler
