diff options
Diffstat (limited to 'hw/ppc')
-rw-r--r-- | hw/ppc/spapr_numa.c | 110 |
1 files changed, 109 insertions, 1 deletions
diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c index 16badb1..b50796b 100644 --- a/hw/ppc/spapr_numa.c +++ b/hw/ppc/spapr_numa.c @@ -37,12 +37,108 @@ static bool spapr_numa_is_symmetrical(MachineState *ms) return true; } +/* + * This function will translate the user distances into + * what the kernel understand as possible values: 10 + * (local distance), 20, 40, 80 and 160, and return the equivalent + * NUMA level for each. Current heuristic is: + * - local distance (10) returns numa_level = 0x4, meaning there is + * no rounding for local distance + * - distances between 11 and 30 inclusive -> rounded to 20, + * numa_level = 0x3 + * - distances between 31 and 60 inclusive -> rounded to 40, + * numa_level = 0x2 + * - distances between 61 and 120 inclusive -> rounded to 80, + * numa_level = 0x1 + * - everything above 120 returns numa_level = 0 to indicate that + * there is no match. This will be calculated as disntace = 160 + * by the kernel (as of v5.9) + */ +static uint8_t spapr_numa_get_numa_level(uint8_t distance) +{ + if (distance == 10) { + return 0x4; + } else if (distance > 11 && distance <= 30) { + return 0x3; + } else if (distance > 31 && distance <= 60) { + return 0x2; + } else if (distance > 61 && distance <= 120) { + return 0x1; + } + + return 0; +} + +static void spapr_numa_define_associativity_domains(SpaprMachineState *spapr) +{ + MachineState *ms = MACHINE(spapr); + NodeInfo *numa_info = ms->numa_state->nodes; + int nb_numa_nodes = ms->numa_state->num_nodes; + int src, dst, i; + + for (src = 0; src < nb_numa_nodes; src++) { + for (dst = src; dst < nb_numa_nodes; dst++) { + /* + * This is how the associativity domain between A and B + * is calculated: + * + * - get the distance D between them + * - get the correspondent NUMA level 'n_level' for D + * - all associativity arrays were initialized with their own + * numa_ids, and we're calculating the distance in node_id + * ascending order, starting from node id 0 (the first node + * retrieved by numa_state). This will have a cascade effect in + * the algorithm because the associativity domains that node 0 + * defines will be carried over to other nodes, and node 1 + * associativities will be carried over after taking node 0 + * associativities into account, and so on. This happens because + * we'll assign assoc_src as the associativity domain of dst + * as well, for all NUMA levels beyond and including n_level. + * + * The PPC kernel expects the associativity domains of node 0 to + * be always 0, and this algorithm will grant that by default. + */ + uint8_t distance = numa_info[src].distance[dst]; + uint8_t n_level = spapr_numa_get_numa_level(distance); + uint32_t assoc_src; + + /* + * n_level = 0 means that the distance is greater than our last + * rounded value (120). In this case there is no NUMA level match + * between src and dst and we can skip the remaining of the loop. + * + * The Linux kernel will assume that the distance between src and + * dst, in this case of no match, is 10 (local distance) doubled + * for each NUMA it didn't match. We have MAX_DISTANCE_REF_POINTS + * levels (4), so this gives us 10*2*2*2*2 = 160. + * + * This logic can be seen in the Linux kernel source code, as of + * v5.9, in arch/powerpc/mm/numa.c, function __node_distance(). + */ + if (n_level == 0) { + continue; + } + + /* + * We must assign all assoc_src to dst, starting from n_level + * and going up to 0x1. + */ + for (i = n_level; i > 0; i--) { + assoc_src = spapr->numa_assoc_array[src][i]; + spapr->numa_assoc_array[dst][i] = assoc_src; + } + } + } + +} + void spapr_numa_associativity_init(SpaprMachineState *spapr, MachineState *machine) { SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr); int nb_numa_nodes = machine->numa_state->num_nodes; int i, j, max_nodes_with_gpus; + bool using_legacy_numa = spapr_machine_using_legacy_numa(spapr); /* * For all associativity arrays: first position is the size, @@ -56,6 +152,17 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr, for (i = 0; i < nb_numa_nodes; i++) { spapr->numa_assoc_array[i][0] = cpu_to_be32(MAX_DISTANCE_REF_POINTS); spapr->numa_assoc_array[i][MAX_DISTANCE_REF_POINTS] = cpu_to_be32(i); + + /* + * Fill all associativity domains of non-zero NUMA nodes with + * node_id. This is required because the default value (0) is + * considered a match with associativity domains of node 0. + */ + if (!using_legacy_numa && i != 0) { + for (j = 1; j < MAX_DISTANCE_REF_POINTS; j++) { + spapr->numa_assoc_array[i][j] = cpu_to_be32(i); + } + } } /* @@ -85,7 +192,7 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr, * 1 NUMA node) will not benefit from anything we're going to do * after this point. */ - if (spapr_machine_using_legacy_numa(spapr)) { + if (using_legacy_numa) { return; } @@ -95,6 +202,7 @@ void spapr_numa_associativity_init(SpaprMachineState *spapr, exit(EXIT_FAILURE); } + spapr_numa_define_associativity_domains(spapr); } void spapr_numa_write_associativity_dt(SpaprMachineState *spapr, void *fdt, |