From bbc9e2f452d9c4b166d1f9a78d941d80173312fe Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 23 Jan 2011 14:37:39 +0100 Subject: x86: Unify cpu/apicid <-> NUMA node mapping between 32 and 64bit The mapping between cpu/apicid and node is done via apicid_to_node[] on 64bit and apicid_2_node[] + apic->x86_32_numa_cpu_node() on 32bit. This difference makes it difficult to further unify 32 and 64bit NUMA handling. This patch unifies it by replacing both apicid_to_node[] and apicid_2_node[] with __apicid_to_node[] array, which is accessed by two accessors - set_apicid_to_node() and numa_cpu_node(). On 64bit, numa_cpu_node() always consults __apicid_to_node[] directly while 32bit goes through apic->numa_cpu_node() method to allow apic implementations to override it. srat_detect_node() for amd cpus contains workaround for broken NUMA configuration which assumes relationship between APIC ID, HT node ID and NUMA topology. Leave it to access __apicid_to_node[] directly as mapping through CPU might result in undesirable behavior change. The comment is reformatted and updated to note the ugliness. Signed-off-by: Tejun Heo Reviewed-by: Pekka Enberg Cc: eric.dumazet@gmail.com Cc: yinghai@kernel.org Cc: brgerst@gmail.com Cc: gorcunov@gmail.com Cc: shaohui.zheng@intel.com Cc: rientjes@google.com LKML-Reference: <1295789862-25482-14-git-send-email-tj@kernel.org> Signed-off-by: Ingo Molnar Cc: David Rientjes --- arch/x86/kernel/cpu/amd.c | 47 ++++++++++++++++++++++++++++++----------------- 1 file changed, 30 insertions(+), 17 deletions(-) (limited to 'arch/x86/kernel/cpu/amd.c') diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 7c7bedb..3cce8f2 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -234,17 +234,21 @@ static void __cpuinit init_amd_k7(struct cpuinfo_x86 *c) #endif #if defined(CONFIG_NUMA) && defined(CONFIG_X86_64) +/* + * To workaround broken NUMA config. Read the comment in + * srat_detect_node(). + */ static int __cpuinit nearby_node(int apicid) { int i, node; for (i = apicid - 1; i >= 0; i--) { - node = apicid_to_node[i]; + node = __apicid_to_node[i]; if (node != NUMA_NO_NODE && node_online(node)) return node; } for (i = apicid + 1; i < MAX_LOCAL_APIC; i++) { - node = apicid_to_node[i]; + node = __apicid_to_node[i]; if (node != NUMA_NO_NODE && node_online(node)) return node; } @@ -339,26 +343,35 @@ static void __cpuinit srat_detect_node(struct cpuinfo_x86 *c) int node; unsigned apicid = c->apicid; - node = per_cpu(cpu_llc_id, cpu); + node = numa_cpu_node(cpu); + if (node == NUMA_NO_NODE) + node = per_cpu(cpu_llc_id, cpu); - if (apicid_to_node[apicid] != NUMA_NO_NODE) - node = apicid_to_node[apicid]; if (!node_online(node)) { - /* Two possibilities here: - - The CPU is missing memory and no node was created. - In that case try picking one from a nearby CPU - - The APIC IDs differ from the HyperTransport node IDs - which the K8 northbridge parsing fills in. - Assume they are all increased by a constant offset, - but in the same order as the HT nodeids. - If that doesn't result in a usable node fall back to the - path for the previous case. */ - + /* + * Two possibilities here: + * + * - The CPU is missing memory and no node was created. In + * that case try picking one from a nearby CPU. + * + * - The APIC IDs differ from the HyperTransport node IDs + * which the K8 northbridge parsing fills in. Assume + * they are all increased by a constant offset, but in + * the same order as the HT nodeids. If that doesn't + * result in a usable node fall back to the path for the + * previous case. + * + * This workaround operates directly on the mapping between + * APIC ID and NUMA node, assuming certain relationship + * between APIC ID, HT node ID and NUMA topology. As going + * through CPU mapping may alter the outcome, directly + * access __apicid_to_node[]. + */ int ht_nodeid = c->initial_apicid; if (ht_nodeid >= 0 && - apicid_to_node[ht_nodeid] != NUMA_NO_NODE) - node = apicid_to_node[ht_nodeid]; + __apicid_to_node[ht_nodeid] != NUMA_NO_NODE) + node = __apicid_to_node[ht_nodeid]; /* Pick a nearby node */ if (!node_online(node)) node = nearby_node(apicid); -- cgit v1.1