Le 30/12/2017 à 07:58, Matthew Wilcox a écrit : > 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"? I guess that would work. Brice -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
