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Message-ID: <20230410155721.3720991-4-sdonthineni@nvidia.com>
Date: Mon, 10 Apr 2023 10:57:21 -0500
From: Shanker Donthineni <sdonthineni@...dia.com>
To: Thomas Gleixner <tglx@...utronix.de>, Marc Zyngier <maz@...nel.org>
CC: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Michael Walle <michael@...le.cc>,
Shanker Donthineni <sdonthineni@...dia.com>,
<linux-kernel@...r.kernel.org>, Vikram Sethi <vsethi@...dia.com>
Subject: [PATCH v3 3/3] genirq: Use the maple tree for IRQ descriptors management
The current implementation uses a static bitmap and a radix tree
to manage IRQ allocation and irq_desc pointer store respectively.
However, the size of the bitmap is constrained by the build time
macro MAX_SPARSE_IRQS, which may not be sufficient to support the
high-end servers, particularly those with GICv4.1 hardware, which
require a large interrupt space to cover LPIs and vSGIs.
The maple tree is a highly efficient data structure for storing
non-overlapping ranges and can handle a large number of entries,
up to ULONG_MAX. It can be utilized for both storing interrupt
descriptors and identifying available free spaces.
The interrupt descriptors management can be simplified by switching
to a maple tree data structure, which offers greater flexibility
and scalability. To support modern servers, the maximum number of
IRQs has been increased to INT_MAX, which provides a more adequate
value than the previous limit of NR_IRQS+8192.
Signed-off-by: Shanker Donthineni <sdonthineni@...dia.com>
---
kernel/irq/internals.h | 2 +-
kernel/irq/irqdesc.c | 54 +++++++++++++++++++++++-------------------
2 files changed, 31 insertions(+), 25 deletions(-)
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index f3f2090dd2de..7bdb7507efb0 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -12,7 +12,7 @@
#include <linux/sched/clock.h>
#ifdef CONFIG_SPARSE_IRQ
-# define MAX_SPARSE_IRQS (NR_IRQS + 8196)
+# define MAX_SPARSE_IRQS INT_MAX
#else
# define MAX_SPARSE_IRQS NR_IRQS
#endif
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 9a71fc6f2c5f..d6d8120ffd56 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -12,8 +12,7 @@
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
-#include <linux/radix-tree.h>
-#include <linux/bitmap.h>
+#include <linux/maple_tree.h>
#include <linux/irqdomain.h>
#include <linux/sysfs.h>
@@ -131,17 +130,38 @@ int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);
static DEFINE_MUTEX(sparse_irq_lock);
-static DECLARE_BITMAP(allocated_irqs, MAX_SPARSE_IRQS);
+static struct maple_tree sparse_irqs = MTREE_INIT_EXT(sparse_irqs,
+ MT_FLAGS_ALLOC_RANGE |
+ MT_FLAGS_LOCK_EXTERN |
+ MT_FLAGS_USE_RCU,
+ sparse_irq_lock);
static int irq_find_free_area(unsigned int from, unsigned int cnt)
{
- return bitmap_find_next_zero_area(allocated_irqs, MAX_SPARSE_IRQS,
- from, cnt, 0);
+ MA_STATE(mas, &sparse_irqs, 0, 0);
+
+ if (mas_empty_area(&mas, from, MAX_SPARSE_IRQS, cnt))
+ return -ENOSPC;
+ return mas.index;
}
static unsigned int irq_find_next_irq(unsigned int offset)
{
- return find_next_bit(allocated_irqs, nr_irqs, offset);
+ struct irq_desc *desc = mt_next(&sparse_irqs, offset, nr_irqs);
+
+ return desc ? irq_desc_get_irq(desc) : nr_irqs;
+}
+
+static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
+{
+ MA_STATE(mas, &sparse_irqs, irq, irq);
+ WARN_ON(mas_store_gfp(&mas, desc, GFP_KERNEL) != 0);
+}
+
+static void delete_irq_desc(unsigned int irq)
+{
+ MA_STATE(mas, &sparse_irqs, irq, irq);
+ mas_erase(&mas);
}
#ifdef CONFIG_SPARSE_IRQ
@@ -355,26 +375,14 @@ static void irq_sysfs_del(struct irq_desc *desc) {}
#endif /* CONFIG_SYSFS */
-static RADIX_TREE(irq_desc_tree, GFP_KERNEL);
-
-static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
-{
- radix_tree_insert(&irq_desc_tree, irq, desc);
-}
-
struct irq_desc *irq_to_desc(unsigned int irq)
{
- return radix_tree_lookup(&irq_desc_tree, irq);
+ return mtree_load(&sparse_irqs, irq);
}
#ifdef CONFIG_KVM_BOOK3S_64_HV_MODULE
EXPORT_SYMBOL_GPL(irq_to_desc);
#endif
-static void delete_irq_desc(unsigned int irq)
-{
- radix_tree_delete(&irq_desc_tree, irq);
-}
-
#ifdef CONFIG_SMP
static void free_masks(struct irq_desc *desc)
{
@@ -517,7 +525,6 @@ static int alloc_descs(unsigned int start, unsigned int cnt, int node,
irq_sysfs_add(start + i, desc);
irq_add_debugfs_entry(start + i, desc);
}
- bitmap_set(allocated_irqs, start, cnt);
return start;
err:
@@ -557,7 +564,6 @@ int __init early_irq_init(void)
for (i = 0; i < initcnt; i++) {
desc = alloc_desc(i, node, 0, NULL, NULL);
- set_bit(i, allocated_irqs);
irq_insert_desc(i, desc);
}
return arch_early_irq_init();
@@ -612,6 +618,7 @@ static void free_desc(unsigned int irq)
raw_spin_lock_irqsave(&desc->lock, flags);
desc_set_defaults(irq, desc, irq_desc_get_node(desc), NULL, NULL);
raw_spin_unlock_irqrestore(&desc->lock, flags);
+ delete_irq_desc(irq);
}
static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
@@ -624,8 +631,8 @@ static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct irq_desc *desc = irq_to_desc(start + i);
desc->owner = owner;
+ irq_insert_desc(start + i, desc);
}
- bitmap_set(allocated_irqs, start, cnt);
return start;
}
@@ -637,7 +644,7 @@ static int irq_expand_nr_irqs(unsigned int nr)
void irq_mark_irq(unsigned int irq)
{
mutex_lock(&sparse_irq_lock);
- bitmap_set(allocated_irqs, irq, 1);
+ irq_insert_desc(irq, irq_desc + irq);
mutex_unlock(&sparse_irq_lock);
}
@@ -781,7 +788,6 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
for (i = 0; i < cnt; i++)
free_desc(from + i);
- bitmap_clear(allocated_irqs, from, cnt);
mutex_unlock(&sparse_irq_lock);
}
EXPORT_SYMBOL_GPL(irq_free_descs);
--
2.25.1
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