On Wed, Dec 27, 2017 at 10:10:34AM +0100, Brice Goglin wrote: > > Perhaps we can enlist /proc/iomem or a similar enumeration interface > > to tell userspace the NUMA node and whether the kernel thinks it has > > better or worse performance characteristics relative to base > > system-RAM, i.e. new IORES_DESC_* values. I'm worried that if we start > > publishing absolute numbers in sysfs userspace will default to looking > > for specific magic numbers in sysfs vs asking the kernel for memory > > that has performance characteristics relative to base "System RAM". In > > other words the absolute performance information that the HMAT > > publishes is useful to the kernel, but it's not clear that userspace > > needs that vs a relative indicator for making NUMA node preference > > decisions. > > Some HPC users will benchmark the machine to discovery actual > performance numbers anyway. > However, most users won't do this. They will want to know relative > performance of different nodes. If you normalize HMAT values by dividing > them with system-RAM values, that's likely OK. If you just say "that > node is faster than system RAM", it's not precise enough. So "this memory has 800% bandwidth of normal" and "this memory has 70% bandwidth of normal"? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
