On 6/30/20 11:36 AM, Shakeel Butt wrote: >> This is part of a larger patch set. If you want to apply these or >> play with them, I'd suggest using the tree from here. It includes >> autonuma-based hot page promotion back to DRAM: >> >> http://lkml.kernel.org/r/c3d6de4d-f7c3-b505-2e64-8ee5f70b2118@xxxxxxxxx >> >> This is also all based on an upstream mechanism that allows >> persistent memory to be onlined and used as if it were volatile: >> >> http://lkml.kernel.org/r/20190124231441.37A4A305@xxxxxxxxxxxxxxxxxx >> > I have a high level question. Given a reclaim request for a set of > nodes, if there is no demotion path out of that set, should the kernel > still consider the migrations within the set of nodes? OK, to be specific, we're talking about a case where we've arrived at try_to_free_pages() and, say, all of the nodes on the system are set in sc->nodemask? Isn't the common case that all nodes are set in sc->nodemask? Since there is never a demotion path out of the set of all nodes, the common case would be that there is no demotion path out of a reclaim node set. If that's true, I'd say that the kernel still needs to consider migrations even within the set.
