docs/specs/ppc-spapr-numa.rst

14 Associativity is defined as a group of platform resources that has
76 means that the second would be 20 and the third level 40. For the P1 and
113   P1 and P2 does not have a common performance boundary. Since this is a one level
115   level, 20.
118 In a hypothetical platform where all resources inside the same hardware module
142 value between the relevant resources. LOPAPR does not provide a standard
144 provides a common-performance hierarchy,  and the ibm,associativity-reference-points
155 * resources one NUMA level apart: 20
178 around for such a long time, with users seeing NUMA distances 10 and 40
192 that to the values that the Linux kernel operates on (10, 20, 40, 80, 160).
195 * user distance 11 to 30 will be interpreted as 20
206 have to accept that a large array of values will be translated to the same
231   1  40  10  20
232   2  80  20  10
259   0  10  40  20  40
261   2  20  80  10  20
262   3  40  40  20  10
279 * distance from 0 to 2 is 20 (no match at 0x4, will match at 0x3)
284 the NUMA level matches. Between 0 and 1, a match in 0x2, we'll also copy
310 between 2 and 3 is 20, i.e. a match in 0x3:
324   0  10  40  20  20
326   2  20  40  10  20
327   3  20  40  20  10
330 0 and 3 is 40, we calculated it as 20. This is what the current logic and
342 As mentioned above, the pSeries NUMA distance logic is, in fact, a way to approximate
348   the distance from node A to B is always the same as B to A. We do not support
349   any A-B pair where the distance back and forth is asymmetric. For example, the
357   1  20  10
361   kind of topology where the distance from a node A to B is X, B to C is X, but
362   the distance A to C is not X. E.g.:
367   0  10  20  20  40
368   1  20  10  80  40
369   2  20  80  10  20
370   3  40  40  20  10
372   In the example above, distance 0 to 2 is 20, 2 to 3 is 20, but 0 to 3 is 40.
375   nodes. This means that a distance equal to 20 between nodes 0 and 2 and the
376   same distance 20 between nodes 2 and 3 will cause the distance between 0 and 3
377   to also be 20.
387 * if it's a NVLink GPU device, distance: 80
390 The way the pseries Linux guest calculates NUMA distances has a direct effect
397 The first and second level are equal, 0x4, and a third one was added in
405 * all resources that aren't a NVLink GPU, it is guaranteed that they will belong