diff options
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 190 |
1 files changed, 143 insertions, 47 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index db3e481cdbb2..294a8ea60298 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -506,33 +506,149 @@ static void __init build_sched_topology(void) } #ifdef CONFIG_NUMA -static int sched_avg_remote_distance; -static int avg_remote_numa_distance(void) +/* + * Test if the on-trace cluster at (N,N) is symmetric. + * Uses upper triangle iteration to avoid obvious duplicates. + */ +static bool slit_cluster_symmetric(int N) { - int i, j; - int distance, nr_remote, total_distance; - - if (sched_avg_remote_distance > 0) - return sched_avg_remote_distance; - - nr_remote = 0; - total_distance = 0; - for_each_node_state(i, N_CPU) { - for_each_node_state(j, N_CPU) { - distance = node_distance(i, j); - - if (distance >= REMOTE_DISTANCE) { - nr_remote++; - total_distance += distance; - } + int u = topology_num_nodes_per_package(); + + for (int k = 0; k < u; k++) { + for (int l = k; l < u; l++) { + if (node_distance(N + k, N + l) != + node_distance(N + l, N + k)) + return false; } } - if (nr_remote) - sched_avg_remote_distance = total_distance / nr_remote; - else - sched_avg_remote_distance = REMOTE_DISTANCE; - return sched_avg_remote_distance; + return true; +} + +/* + * Return the package-id of the cluster, or ~0 if indeterminate. + * Each node in the on-trace cluster should have the same package-id. + */ +static u32 slit_cluster_package(int N) +{ + int u = topology_num_nodes_per_package(); + u32 pkg_id = ~0; + + for (int n = 0; n < u; n++) { + const struct cpumask *cpus = cpumask_of_node(N + n); + int cpu; + + for_each_cpu(cpu, cpus) { + u32 id = topology_logical_package_id(cpu); + + if (pkg_id == ~0) + pkg_id = id; + if (pkg_id != id) + return ~0; + } + } + + return pkg_id; +} + +/* + * Validate the SLIT table is of the form expected for SNC, specifically: + * + * - each on-trace cluster should be symmetric, + * - each on-trace cluster should have a unique package-id. + * + * If you NUMA_EMU on top of SNC, you get to keep the pieces. + */ +static bool slit_validate(void) +{ + int u = topology_num_nodes_per_package(); + u32 pkg_id, prev_pkg_id = ~0; + + for (int pkg = 0; pkg < topology_max_packages(); pkg++) { + int n = pkg * u; + + /* + * Ensure the on-trace cluster is symmetric and each cluster + * has a different package id. + */ + if (!slit_cluster_symmetric(n)) + return false; + pkg_id = slit_cluster_package(n); + if (pkg_id == ~0) + return false; + if (pkg && pkg_id == prev_pkg_id) + return false; + + prev_pkg_id = pkg_id; + } + + return true; +} + +/* + * Compute a sanitized SLIT table for SNC; notably SNC-3 can end up with + * asymmetric off-trace clusters, reflecting physical assymmetries. However + * this leads to 'unfortunate' sched_domain configurations. + * + * For example dual socket GNR with SNC-3: + * + * node distances: + * node 0 1 2 3 4 5 + * 0: 10 15 17 21 28 26 + * 1: 15 10 15 23 26 23 + * 2: 17 15 10 26 23 21 + * 3: 21 28 26 10 15 17 + * 4: 23 26 23 15 10 15 + * 5: 26 23 21 17 15 10 + * + * Fix things up by averaging out the off-trace clusters; resulting in: + * + * node 0 1 2 3 4 5 + * 0: 10 15 17 24 24 24 + * 1: 15 10 15 24 24 24 + * 2: 17 15 10 24 24 24 + * 3: 24 24 24 10 15 17 + * 4: 24 24 24 15 10 15 + * 5: 24 24 24 17 15 10 + */ +static int slit_cluster_distance(int i, int j) +{ + static int slit_valid = -1; + int u = topology_num_nodes_per_package(); + long d = 0; + int x, y; + + if (slit_valid < 0) { + slit_valid = slit_validate(); + if (!slit_valid) + pr_err(FW_BUG "SLIT table doesn't have the expected form for SNC -- fixup disabled!\n"); + else + pr_info("Fixing up SNC SLIT table.\n"); + } + + /* + * Is this a unit cluster on the trace? + */ + if ((i / u) == (j / u) || !slit_valid) + return node_distance(i, j); + + /* + * Off-trace cluster. + * + * Notably average out the symmetric pair of off-trace clusters to + * ensure the resulting SLIT table is symmetric. + */ + x = i - (i % u); + y = j - (j % u); + + for (i = x; i < x + u; i++) { + for (j = y; j < y + u; j++) { + d += node_distance(i, j); + d += node_distance(j, i); + } + } + + return d / (2*u*u); } int arch_sched_node_distance(int from, int to) @@ -542,34 +658,14 @@ int arch_sched_node_distance(int from, int to) switch (boot_cpu_data.x86_vfm) { case INTEL_GRANITERAPIDS_X: case INTEL_ATOM_DARKMONT_X: - - if (topology_max_packages() == 1 || topology_num_nodes_per_package() == 1 || - d < REMOTE_DISTANCE) + if (topology_max_packages() == 1 || + topology_num_nodes_per_package() < 3) return d; /* - * With SNC enabled, there could be too many levels of remote - * NUMA node distances, creating NUMA domain levels - * including local nodes and partial remote nodes. - * - * Trim finer distance tuning for NUMA nodes in remote package - * for the purpose of building sched domains. Group NUMA nodes - * in the remote package in the same sched group. - * Simplify NUMA domains and avoid extra NUMA levels including - * different remote NUMA nodes and local nodes. - * - * GNR and CWF don't expect systems with more than 2 packages - * and more than 2 hops between packages. Single average remote - * distance won't be appropriate if there are more than 2 - * packages as average distance to different remote packages - * could be different. + * Handle SNC-3 asymmetries. */ - WARN_ONCE(topology_max_packages() > 2, - "sched: Expect only up to 2 packages for GNR or CWF, " - "but saw %d packages when building sched domains.", - topology_max_packages()); - - d = avg_remote_numa_distance(); + return slit_cluster_distance(from, to); } return d; } |