From 99bd0c0fc4b04da54cb311953ef9489931c19c63 Mon Sep 17 00:00:00 2001 From: Andreas Herrmann Date: Fri, 19 Jun 2009 10:59:09 +0200 Subject: [PATCH] x86: Set cpu_llc_id on AMD CPUs This counts when building sched domains in case NUMA information is not available. ( See cpu_coregroup_mask() which uses llc_shared_map which in turn is created based on cpu_llc_id. ) Currently Linux builds domains as follows: (example from a dual socket quad-core system) CPU0 attaching sched-domain: domain 0: span 0-7 level CPU groups: 0 1 2 3 4 5 6 7 ... CPU7 attaching sched-domain: domain 0: span 0-7 level CPU groups: 7 0 1 2 3 4 5 6 Ever since that is borked for multi-core AMD CPU systems. This patch fixes that and now we get a proper: CPU0 attaching sched-domain: domain 0: span 0-3 level MC groups: 0 1 2 3 domain 1: span 0-7 level CPU groups: 0-3 4-7 ... CPU7 attaching sched-domain: domain 0: span 4-7 level MC groups: 7 4 5 6 domain 1: span 0-7 level CPU groups: 4-7 0-3 This allows scheduler to assign tasks to cores on different sockets (i.e. that don't share last level cache) for performance reasons. Signed-off-by: Andreas Herrmann LKML-Reference: <20090619085909.GJ5218@alberich.amd.com> Cc: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/amd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index e5b27d8f1b47..28e5f5956042 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -258,13 +258,15 @@ static void __cpuinit amd_detect_cmp(struct cpuinfo_x86 *c) { #ifdef CONFIG_X86_HT unsigned bits; + int cpu = smp_processor_id(); bits = c->x86_coreid_bits; - /* Low order bits define the core id (index of core in socket) */ c->cpu_core_id = c->initial_apicid & ((1 << bits)-1); /* Convert the initial APIC ID into the socket ID */ c->phys_proc_id = c->initial_apicid >> bits; + /* use socket ID also for last level cache */ + per_cpu(cpu_llc_id, cpu) = c->phys_proc_id; #endif } -- GitLab