Messages in this thread | | | Subject | Re: [PATCH v2] ppc64/numa: consider the max numa node for migratable LPAR | From | Laurent Dufour <> | Date | Thu, 1 Jul 2021 10:36:12 +0200 |
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Hi Michael,
Do you mind taking this patch of 5.14?
Thanks, Laurent.
Le 11/05/2021 à 09:31, Laurent Dufour a écrit : > When a LPAR is migratable, we should consider the maximum possible NUMA > node instead the number of NUMA node from the actual system. > > The DT property 'ibm,current-associativity-domains' is defining the maximum > number of nodes the LPAR can see when running on that box. But if the LPAR > is being migrated on another box, it may seen up to the nodes defined by > 'ibm,max-associativity-domains'. So if a LPAR is migratable, that value > should be used. > > Unfortunately, there is no easy way to know if a LPAR is migratable or > not. The hypervisor is exporting the property 'ibm,migratable-partition' in > the case it set to migrate partition, but that would not mean that the > current partition is migratable. > > Without this patch, when a LPAR is started on a 2 nodes box and then > migrated to a 3 nodes box, the hypervisor may spread the LPAR's CPUs on the > 3rd node. In that case if a CPU from that 3rd node is added to the LPAR, it > will be wrongly assigned to the node because the kernel has been set to use > up to 2 nodes (the configuration of the departure node). With this patch > applies, the CPU is correctly added to the 3rd node. > > Fixes: f9f130ff2ec9 ("powerpc/numa: Detect support for coregroup") > Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> > Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> > --- > V2: Address Srikar's comments > - Fix the commit message > - Use pr_info instead printk(KERN_INFO..) > --- > arch/powerpc/mm/numa.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c > index f2bf98bdcea2..094a1076fd1f 100644 > --- a/arch/powerpc/mm/numa.c > +++ b/arch/powerpc/mm/numa.c > @@ -893,7 +893,7 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn) > static void __init find_possible_nodes(void) > { > struct device_node *rtas; > - const __be32 *domains; > + const __be32 *domains = NULL; > int prop_length, max_nodes; > u32 i; > > @@ -909,9 +909,14 @@ static void __init find_possible_nodes(void) > * it doesn't exist, then fallback on ibm,max-associativity-domains. > * Current denotes what the platform can support compared to max > * which denotes what the Hypervisor can support. > + * > + * If the LPAR is migratable, new nodes might be activated after a LPM, > + * so we should consider the max number in that case. > */ > - domains = of_get_property(rtas, "ibm,current-associativity-domains", > - &prop_length); > + if (!of_get_property(of_root, "ibm,migratable-partition", NULL)) > + domains = of_get_property(rtas, > + "ibm,current-associativity-domains", > + &prop_length); > if (!domains) { > domains = of_get_property(rtas, "ibm,max-associativity-domains", > &prop_length); > @@ -920,6 +925,8 @@ static void __init find_possible_nodes(void) > } > > max_nodes = of_read_number(&domains[min_common_depth], 1); > + pr_info("Partition configured for %d NUMA nodes.\n", max_nodes); > + > for (i = 0; i < max_nodes; i++) { > if (!node_possible(i)) > node_set(i, node_possible_map); >
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