forked from Minki/linux
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 <andreas.herrmann3@amd.com> LKML-Reference: <20090619085909.GJ5218@alberich.amd.com> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -258,13 +258,15 @@ static void __cpuinit amd_detect_cmp(struct cpuinfo_x86 *c)
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{
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#ifdef CONFIG_X86_HT
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unsigned bits;
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int cpu = smp_processor_id();
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bits = c->x86_coreid_bits;
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/* Low order bits define the core id (index of core in socket) */
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c->cpu_core_id = c->initial_apicid & ((1 << bits)-1);
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/* Convert the initial APIC ID into the socket ID */
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c->phys_proc_id = c->initial_apicid >> bits;
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/* use socket ID also for last level cache */
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per_cpu(cpu_llc_id, cpu) = c->phys_proc_id;
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#endif
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}
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