Messages in this thread Patch in this message | | | Date | Tue, 30 Jun 2009 17:24:10 -0700 | From | Greg KH <> | Subject | [patch 081/108] x86: Set cpu_llc_id on AMD CPUs |
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2.6.30-stable review patch. If anyone has any objections, please let us know.
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From: Andreas Herrmann <andreas.herrmann3@amd.com>
commit 99bd0c0fc4b04da54cb311953ef9489931c19c63 upstream.
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> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/kernel/cpu/amd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -258,13 +258,15 @@ static void __cpuinit amd_detect_cmp(str { #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 }
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