From: Dave Hansen <[email protected]> Our SMP boot code has a series of assumptions about what NUMA nodes are that are enforced via topology_sane(). Once upon a time, we verified that a CPU package only contained a single node (fixed in cebf15eb0). Today, we verify that SMT siblings and LLCs do not span nodes.
The SMT siblings assumption is safe, but the LLC is violated on current hardware. Remove the "sanity" check on LLC spanning NUMA nodes. Also make sure to set 'x86_has_numa_in_package = true' which ensures that we use the x86_numa_in_package_topology[]. The default topology layers NUMA "outside" of the cache, which is wrong when the cache spans multiple nodes. This fixes the warnings, but it does theoretically throw away the LLC from being consulted in scheduling decisions, if the LLC is shared at a boundary that is not also a NUMA node. Signed-off-by: Dave Hansen <[email protected]> Cc: Luck, Tony <[email protected]> Cc: Tim Chen <[email protected]> Cc: Peter Zijlstra (Intel) <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: David Rientjes <[email protected]> Cc: Igor Mammedov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Prarit Bhargava <[email protected]> Cc: Toshi Kani <[email protected]> Cc: [email protected] Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> --- b/arch/x86/kernel/smpboot.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff -puN arch/x86/kernel/smpboot.c~x86-numa-nodes-share-llc arch/x86/kernel/smpboot.c --- a/arch/x86/kernel/smpboot.c~x86-numa-nodes-share-llc 2017-06-01 14:46:40.562159566 -0700 +++ b/arch/x86/kernel/smpboot.c 2017-06-01 15:01:43.994157313 -0700 @@ -460,7 +460,7 @@ static bool match_llc(struct cpuinfo_x86 if (per_cpu(cpu_llc_id, cpu1) != BAD_APICID && per_cpu(cpu_llc_id, cpu1) == per_cpu(cpu_llc_id, cpu2)) - return topology_sane(c, o, "llc"); + return true; return false; } @@ -520,7 +520,8 @@ static struct sched_domain_topology_leve /* * Set if a package/die has multiple NUMA nodes inside. - * AMD Magny-Cours and Intel Cluster-on-Die have this. + * AMD Magny-Cours, Intel Cluster-on-Die, and Intel + * Sub-NUMA Clustering have this. */ static bool x86_has_numa_in_package; @@ -548,9 +549,13 @@ void set_cpu_sibling_map(int cpu) if ((i == cpu) || (has_smt && match_smt(c, o))) link_mask(topology_sibling_cpumask, cpu, i); - if ((i == cpu) || (has_mp && match_llc(c, o))) - link_mask(cpu_llc_shared_mask, cpu, i); - + if ((i == cpu) || (has_mp && match_llc(c, o))) { + /* LLC may be shared across NUMA nodes */ + if (topology_same_node(c, o)) + link_mask(cpu_llc_shared_mask, cpu, i); + else + x86_has_numa_in_package = true; + } } /* _
