On Mon 12-08-19 19:40:10, Khalid Aziz wrote: [...] > Patch 1 adds code to maintain a sliding lookback window of (time, number > of free pages) points which can be updated continuously and adds code to > compute best fit line across these points. It also adds code to use the > best fit lines to determine if kernel must start reclamation or > compaction. > > Patch 2 adds code to collect data points on free pages of various orders > at different points in time, uses code in patch 1 to update sliding > lookback window with these points and kicks off reclamation or > compaction based upon the results it gets. An important piece of information missing in your description is why do we need to keep that logic in the kernel. In other words, we have the background reclaim that acts on a wmark range and those are tunable from the userspace. The primary point of this background reclaim is to keep balance and prevent from direct reclaim. Why cannot you implement this or any other dynamic trend watching watchdog and tune watermarks accordingly? Something similar applies to kcompactd although we might be lacking a good interface. -- Michal Hocko SUSE Labs
