Messages in this thread Patch in this message |  | | From | Shanker Donthineni <> | Subject | [PATCH 5/5] genirq: Use the maple tree for IRQ descriptors management | Date | Sun, 29 Jan 2023 18:57:25 -0600 |
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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 IRQD and identifying available free spaces.
The IRQD 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@nvidia.com> --- kernel/irq/internals.h | 2 +- kernel/irq/irqdesc.c | 51 ++++++++++++++++++++++++------------------ 2 files changed, 30 insertions(+), 23 deletions(-)
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index 5d741b0e7d5e..e35de737802c 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 247a0718d028..06be5f924a7c 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -15,6 +15,7 @@ #include <linux/radix-tree.h> #include <linux/bitmap.h> #include <linux/irqdomain.h> +#include <linux/maple_tree.h> #include <linux/sysfs.h> #include "internals.h" @@ -131,17 +132,37 @@ 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); } static int irq_expand_nr_irqs(unsigned int nr) @@ -363,26 +384,14 @@ 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) { @@ -527,7 +536,6 @@ 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: @@ -559,7 +567,6 @@ 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(); @@ -613,6 +620,7 @@ 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, @@ -625,15 +633,15 @@ 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; } void irq_mark_irq(unsigned int irq) { mutex_lock(&sparse_irq_lock); - bitmap_set(allocated_irqs, irq, 1); + irq_insert_desc(irq, irq_descs + irq); mutex_unlock(&sparse_irq_lock); } @@ -777,7 +785,6 @@ 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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