On Mon, Jan 13, 2025 at 7:06 PM Gregory Price <gourry@xxxxxxxxxx> wrote: > 5) Scarce resources > > We need to be careful not to consume excessive amounts of resources > in an attempt to track all these identifying mechanisms. Even 1 byte > per folio is 256MB on a 1TB machine. This gets out of hand quick. > > With task-work, I was able to add no additional resource consumption, > but deferring to a fully async scenario and needing to track things > like last-accessing CPU, timestamps, and etc. > > We'll need to examine this closely if we decide to aggregate either > of these mechanisms. My concern with physical address space monitoring is fragmentation. I ran some numbers on a few prod machines. Grouping by regions with the same memcg and ignoring any unmapped memory to be generous, machines with higher utilization can have a region/total pages ratio of ~40%, and even those with lower utilization (<50%) can also reach 20%. Accurately tracking these regions would require quite the region metadata, on the order of GBs.
