On Wed, 2009-11-11 at 13:13 +1030, Rusty Russell wrote: > > It's not laziness, it's consistency. How is actual different than free > > memory or any other stat? > > Because it's a COLLECTION of stats. For example, swap in should be < swap > out. Now, the current Linux implementation of all_vm_events() is non-atomic > anyway, so maybe we can just document this as best-effort. I'm saying that > if it *is* a problem, I think we need a vq. I can't see why we would care about the atomicity of the collection of statistics. Best-effort is good enough. Any variance within the stats will be overshadowed by the latency of the host-side management daemon. > But it raises the question: what stats are generally useful cross-OS? Should > we be supplying numbers like "unused" (free) "instantly discardable" (ie. > clean), "discardable to disk" (ie. file-backed), "discardable to swap" > (ie. swap-backed) and "unswappable" instead? While I see the virtue in presenting abstracted memory stats that seem more digestible in a virtualization context, I think we should keep the raw stats. This concentrates the complexity in the host-side management daemon, and allows the host daemon to make better decisions (ie. by reacting to trends in individual statistics). Different OSes (or different versions of the same OS), may also have different sets of statistics that will provide the answers that a management daemon needs. -- Thanks, Adam _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
