linux-kernel - [RFC 2/2] genirq/matrix: take NUMA into account for managed IRQs

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Date:   Wed, 17 Jun 2020 10:37:25 +0100
From:   Stefan Hajnoczi <stefanha@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Marcelo Tosatti <mtosatti@...hat.com>, linux-pci@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>
Subject: [RFC 2/2] genirq/matrix: take NUMA into account for managed IRQs

Select CPUs from the IRQ's NUMA node in preference over other CPUs. This
ensures that managed IRQs are assigned to the same NUMA node as the
device.

Signed-off-by: Stefan Hajnoczi <stefanha@...hat.com>
---
 include/linux/irq.h           |  2 +-
 arch/x86/kernel/apic/vector.c |  3 ++-
 kernel/irq/matrix.c           | 16 ++++++++++++----
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 8d5bc2c237d7..bdc3faa3c280 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -1202,7 +1202,7 @@ void irq_matrix_assign_system(struct irq_matrix *m, unsigned int bit, bool repla
 int irq_matrix_reserve_managed(struct irq_matrix *m, const struct cpumask *msk);
 void irq_matrix_remove_managed(struct irq_matrix *m, const struct cpumask *msk);
 int irq_matrix_alloc_managed(struct irq_matrix *m, const struct cpumask *msk,
-				unsigned int *mapped_cpu);
+			     int node, unsigned int *mapped_cpu);
 void irq_matrix_reserve(struct irq_matrix *m);
 void irq_matrix_remove_reserved(struct irq_matrix *m);
 int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk,
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 67768e54438b..8eb10b0d981d 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -309,6 +309,7 @@ assign_managed_vector(struct irq_data *irqd, const struct cpumask *dest)
 {
 	const struct cpumask *affmsk = irq_data_get_affinity_mask(irqd);
 	struct apic_chip_data *apicd = apic_chip_data(irqd);
+	int node = irq_data_get_node(irqd);
 	int vector, cpu;
 
 	cpumask_and(vector_searchmask, dest, affmsk);
@@ -317,7 +318,7 @@ assign_managed_vector(struct irq_data *irqd, const struct cpumask *dest)
 	if (apicd->vector && cpumask_test_cpu(apicd->cpu, vector_searchmask))
 		return 0;
 	vector = irq_matrix_alloc_managed(vector_matrix, vector_searchmask,
-					  &cpu);
+					  node, &cpu);
 	trace_vector_alloc_managed(irqd->irq, vector, vector);
 	if (vector < 0)
 		return vector;
diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
index 30cc217b8631..ee35b6172b64 100644
--- a/kernel/irq/matrix.c
+++ b/kernel/irq/matrix.c
@@ -148,7 +148,8 @@ static unsigned int matrix_find_best_cpu(struct irq_matrix *m,
 
 /* Find the best CPU which has the lowest number of managed IRQs allocated */
 static unsigned int matrix_find_best_cpu_managed(struct irq_matrix *m,
-						const struct cpumask *msk)
+						 const struct cpumask *msk,
+						 int node)
 {
 	unsigned int cpu, best_cpu, allocated = UINT_MAX;
 	struct cpumap *cm;
@@ -156,6 +157,9 @@ static unsigned int matrix_find_best_cpu_managed(struct irq_matrix *m,
 	best_cpu = UINT_MAX;
 
 	for_each_cpu(cpu, msk) {
+		if (node != NUMA_NO_NODE && cpu_to_node(cpu) != node)
+			continue;
+
 		cm = per_cpu_ptr(m->maps, cpu);
 
 		if (!cm->online || cm->managed_allocated > allocated)
@@ -280,10 +284,12 @@ void irq_matrix_remove_managed(struct irq_matrix *m, const struct cpumask *msk)
 /**
  * irq_matrix_alloc_managed - Allocate a managed interrupt in a CPU map
  * @m:		Matrix pointer
- * @cpu:	On which CPU the interrupt should be allocated
+ * @mask:	The mask of CPUs on which the interrupt can be allocated
+ * @node:	The preferred NUMA node
+ * @mapped_cpu:	The resulting CPU on which the interrupt should be allocated
  */
 int irq_matrix_alloc_managed(struct irq_matrix *m, const struct cpumask *msk,
-			     unsigned int *mapped_cpu)
+			     int node, unsigned int *mapped_cpu)
 {
 	unsigned int bit, cpu, end = m->alloc_end;
 	struct cpumap *cm;
@@ -291,7 +297,9 @@ int irq_matrix_alloc_managed(struct irq_matrix *m, const struct cpumask *msk,
 	if (cpumask_empty(msk))
 		return -EINVAL;
 
-	cpu = matrix_find_best_cpu_managed(m, msk);
+	cpu = matrix_find_best_cpu_managed(m, msk, node);
+	if (cpu == UINT_MAX)
+		cpu = matrix_find_best_cpu_managed(m, msk, NUMA_NO_NODE);
 	if (cpu == UINT_MAX)
 		return -ENOSPC;
 
-- 
2.26.2