> Figuring out if SNC is enabled is only one part of the problem, the > other being whether the kernel supports it. As there is no easy > interface that simply states SNC support in the kernel one can find that > information by comparing L3 cache sizes from different sources. Cache > size reported by /sys/devices/system/node/node0/cpu0/cache/index3/size > will always show the full cache size even if it's split by enabled SNC. > On the other hand /sys/fs/resctrl/size has information about L3 size, > that with kernel support is adjusted for enabled SNC. Early versions of the kernel SNC patch series added an info/l3_MON/snc_ways file to provide this information. I was talked out of it then: https://lore.kernel.org/all/f0841866-315b-4727-0a6c-ec60d22ca29c@xxxxxxx/ But that discussion didn't consider the question you discuss here: "Does this instance of the kernel support SNC?" So you have a clever solution. But it seems like a roundabout way for an application to discover whether the kernel has configured resctrl for SNC mode. Should the kernel provide an info/ file listing the SNC configuration? If so, what should it be named? "snc_ways" as a kernel variable was later replaced by "snc_nodes_per_l3_cache". Is that a good filename? -Tony
