On Wed, Nov 8, 2023 at 12:11 AM Huang, Ying <ying.huang@xxxxxxxxx> wrote: > > Huan Yang <link@xxxxxxxx> writes: > > > HI Huang, Ying > > > > Thanks for reply. > > > > 在 2023/11/8 15:35, Huang, Ying 写道: > >> Huan Yang <link@xxxxxxxx> writes: > >> > >>> In some cases, we need to selectively reclaim file pages or anonymous > >>> pages in an unbalanced manner. > >>> > >>> For example, when an application is pushed to the background and frozen, > >>> it may not be opened for a long time, and we can safely reclaim the > >>> application's anonymous pages, but we do not want to touch the file pages. > >>> > >>> This patchset extends the proactive reclaim interface to achieve > >>> unbalanced reclamation. Users can control the reclamation tendency by > >>> inputting swappiness under the original interface. Specifically, users > >>> can input special values to extremely reclaim specific pages. > >> From mem_cgroup_swappiness(), cgroupv2 doesn't have per-cgroup > >> swappiness. So you need to add that firstly? > > Sorry for this mistake, we always work on cgroupv1, so, not notice > > this commit 4550c4e, thank your for point that. > > > > I see this commit comment that `that's a different discussion`, but, > > to implements this, I will try add. > > > >> > >>> Example: > >>> echo "1G" 200 > memory.reclaim (only reclaim anon) > >>> echo "1G" 0 > memory.reclaim (only reclaim file) > >>> echo "1G" 1 > memory.reclaim (only reclaim file) > >>> > >>> Note that when performing unbalanced reclamation, the cgroup swappiness > >>> will be temporarily adjusted dynamically to the input value. Therefore, > >>> if the cgroup swappiness is further modified during runtime, there may > >>> be some errors. > >> If cgroup swappiness will be adjusted temporarily, why not just change > >> it via a script before/after proactive reclaiming? > > IMO, this unbalance reclaim only takes effect for a single command, > > so if it is pre-set using a script, the judgment of the reclamation tendency > > may become complicated. > > If swappiness == 0, then we will only reclaim file pages. If swappiness > == 200, then we may still reclaim file pages. So you need a way to > reclaim only anon pages? > > If so, can we use some special swappiness value to specify that? I > don't know whether use 200 will cause regression. If so, we may need > some other value, e.g. >= 65536. I don't think swappiness is the answer here. This has been discussed a while back, please see my response. As you mentioned, swappiness may be ignored by the kernel in some cases, and its behavior has historically changed before.
