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[PATCH 3/3] spapr_numa.c: fix ibm, max-associativity-domains calculation
From: |
Daniel Henrique Barboza |
Subject: |
[PATCH 3/3] spapr_numa.c: fix ibm, max-associativity-domains calculation |
Date: |
Thu, 28 Jan 2021 12:17:31 -0300 |
The current logic for calculating 'maxdomain' making it a sum of
numa_state->num_nodes with spapr->gpu_numa_id. spapr->gpu_numa_id is
used as a index to determine the next available NUMA id that a
given NVGPU can use.
The problem is that the initial value of gpu_numa_id, for any topology
that has more than one NUMA node, is equal to numa_state->num_nodes.
This means that our maxdomain will always be, at least, twice the
amount of existing NUMA nodes. This means that a guest with 4 NUMA
nodes will end up with the following max-associativity-domains:
rtas/ibm,max-associativity-domains
00000004 00000008 00000008 00000008 00000008
This overtuning of maxdomains doesn't go unnoticed in the guest, being
detected in SLUB during boot:
dmesg | grep SLUB
[ 0.000000] SLUB: HWalign=128, Order=0-3, MinObjects=0, CPUs=4, Nodes=8
SLUB is detecting 8 total nodes, with 4 nodes being online.
This patch fixes ibm,max-associativity-domains by considering the amount
of NVGPUs NUMA nodes presented in the guest, instead of
spapr->gpu_numa_id.
Reported-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
hw/ppc/spapr_numa.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/hw/ppc/spapr_numa.c b/hw/ppc/spapr_numa.c
index f71105c783..f4d6abce87 100644
--- a/hw/ppc/spapr_numa.c
+++ b/hw/ppc/spapr_numa.c
@@ -60,6 +60,19 @@ unsigned int spapr_numa_initial_nvgpu_NUMA_id(MachineState
*machine)
return MAX(1, machine->numa_state->num_nodes);
}
+/*
+ * Note: if called before spapr_phb_pci_collect_nvgpu() finishes collecting
+ * all NVGPUs, this function will not give the right number of NVGPUs NUMA
+ * nodes.
+ */
+static
+unsigned int spapr_numa_get_number_nvgpus_nodes(SpaprMachineState *spapr)
+{
+ MachineState *ms = MACHINE(spapr);
+
+ return spapr->gpu_numa_id - spapr_numa_initial_nvgpu_NUMA_id(ms);
+}
+
/*
* This function will translate the user distances into
* what the kernel understand as possible values: 10
@@ -311,6 +324,7 @@ void spapr_numa_write_rtas_dt(SpaprMachineState *spapr,
void *fdt, int rtas)
{
MachineState *ms = MACHINE(spapr);
SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
+ uint32_t number_nvgpus_nodes = spapr_numa_get_number_nvgpus_nodes(spapr);
uint32_t refpoints[] = {
cpu_to_be32(0x4),
cpu_to_be32(0x3),
@@ -318,7 +332,7 @@ void spapr_numa_write_rtas_dt(SpaprMachineState *spapr,
void *fdt, int rtas)
cpu_to_be32(0x1),
};
uint32_t nr_refpoints = ARRAY_SIZE(refpoints);
- uint32_t maxdomain = ms->numa_state->num_nodes + spapr->gpu_numa_id;
+ uint32_t maxdomain = ms->numa_state->num_nodes + number_nvgpus_nodes;
uint32_t maxdomains[] = {
cpu_to_be32(4),
cpu_to_be32(maxdomain),
--
2.26.2