On 4/18/22 09:45, Davidlohr Bueso wrote: > On Mon, 18 Apr 2022, Dave Hansen wrote: >> On 4/16/22 20:49, Davidlohr Bueso wrote: >>> This allows userspace to know if the node is considered fast >>> memory (with CPUs attached to it). While this can be already >>> derived without a new file, this helps further encapsulate the >>> concept. >> >> What is userspace supposed to *do* with this, though? > > This came as a scratch to my own itch. I wanted to start testing > more tiering patches overall that I see pop up, and wanted a way > to differentiate the slow vs the fast memories in order to better > configure workload(s) working set sizes beyond what is your typical > grep MemTotal /proc/meminfo. If there is a better way I'm all > for it. But how does this help you? Does it save you a few lines in a shell script to find the nodes that have memory and CPUs? >> Isn't it just asking for trouble to add (known) redundancy to the ABI? >> It seems like a recipe for future inconsistency. > > Perhaps. It was mostly about the fact that the notion of top tier > could also change as technology evolves. It seems like something arbitrary that everyone will just disagree on. I think we should try to stick to cold, hard facts as must as possible rather than trying to have the *kernel* dictate as a policy what is fast versus slow.
