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mm/vmalloc: eliminated the lock contention from twice to once

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When allocating a new memory area where the mapping address range is
known, it is observed that the vmap_node->busy.lock is acquired twice.

The first acquisition occurs in the alloc_vmap_area() function when
inserting the vm area into the vm mapping red-black tree.  The second
acquisition occurs in the setup_vmalloc_vm() function when updating the
properties of the vm, such as flags and address, etc.

Combine these two operations together in alloc_vmap_area(), which improves
scalability when the vmap_node->busy.lock is contended.  By doing so, the
need to acquire the lock twice can also be eliminated to once.

With the above change, tested on intel sapphire rapids platform(224 vcpu),
a 4% performance improvement is gained on
stress-ng/pthread(https://github.com/ColinIanKing/stress-ng), which is the
stress test of thread creations.

Link: https://lkml.kernel.org/r/20240307021440.64967-1-rulin.huang@intel.com
Co-developed-by: "Chen, Tim C" <tim.c.chen@intel.com>
Signed-off-by: "Chen, Tim C" <tim.c.chen@intel.com>
Co-developed-by: "King, Colin" <colin.king@intel.com>
Signed-off-by: "King, Colin" <colin.king@intel.com>
Signed-off-by: rulinhuang <rulin.huang@intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Wangyang Guo <wangyang.guo@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
rulinhuang 2024-03-06 21:14:40 -05:00 committed by Andrew Morton
parent c8d36bc2df
commit aaab830ad8
1 changed files with 22 additions and 28 deletions
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50
mm/vmalloc.c
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@ -1926,15 +1926,26 @@ node_alloc(unsigned long size, unsigned long align,
return va;
}
static inline void setup_vmalloc_vm(struct vm_struct *vm,
struct vmap_area *va, unsigned long flags, const void *caller)
{
vm->flags = flags;
vm->addr = (void *)va->va_start;
vm->size = va->va_end - va->va_start;
vm->caller = caller;
va->vm = vm;
}
/*
* Allocate a region of KVA of the specified size and alignment, within the
* vstart and vend.
* vstart and vend. If vm is passed in, the two will also be bound.
*/
static struct vmap_area *alloc_vmap_area(unsigned long size,
unsigned long align,
unsigned long vstart, unsigned long vend,
int node, gfp_t gfp_mask,
unsigned long va_flags)
unsigned long va_flags, struct vm_struct *vm,
unsigned long flags, const void *caller)
{
struct vmap_node *vn;
struct vmap_area *va;
@ -1997,6 +2008,9 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
va->vm = NULL;
va->flags = (va_flags | vn_id);
if (vm)
setup_vmalloc_vm(vm, va, flags, caller);
vn = addr_to_node(va->va_start);
spin_lock(&vn->busy.lock);
@ -2574,7 +2588,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
VMALLOC_START, VMALLOC_END,
node, gfp_mask,
VMAP_RAM|VMAP_BLOCK);
VMAP_RAM|VMAP_BLOCK, NULL,
0, NULL);
if (IS_ERR(va)) {
kfree(vb);
return ERR_CAST(va);
@ -2931,7 +2946,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node)
struct vmap_area *va;
va = alloc_vmap_area(size, PAGE_SIZE,
VMALLOC_START, VMALLOC_END,
node, GFP_KERNEL, VMAP_RAM);
node, GFP_KERNEL, VMAP_RAM,
NULL, 0, NULL);
if (IS_ERR(va))
return NULL;
@ -3034,26 +3050,6 @@ void __init vm_area_register_early(struct vm_struct *vm, size_t align)
kasan_populate_early_vm_area_shadow(vm->addr, vm->size);
}
static inline void setup_vmalloc_vm_locked(struct vm_struct *vm,
struct vmap_area *va, unsigned long flags, const void *caller)
{
vm->flags = flags;
vm->addr = (void *)va->va_start;
vm->size = va->va_end - va->va_start;
vm->caller = caller;
va->vm = vm;
}
static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
unsigned long flags, const void *caller)
{
struct vmap_node *vn = addr_to_node(va->va_start);
spin_lock(&vn->busy.lock);
setup_vmalloc_vm_locked(vm, va, flags, caller);
spin_unlock(&vn->busy.lock);
}
static void clear_vm_uninitialized_flag(struct vm_struct *vm)
{
/*
@ -3090,14 +3086,12 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
if (!(flags & VM_NO_GUARD))
size += PAGE_SIZE;
va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0);
va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0, area, flags, caller);
if (IS_ERR(va)) {
kfree(area);
return NULL;
}
setup_vmalloc_vm(area, va, flags, caller);
/*
* Mark pages for non-VM_ALLOC mappings as accessible. Do it now as a
* best-effort approach, as they can be mapped outside of vmalloc code.
@ -4672,7 +4666,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
spin_lock(&vn->busy.lock);
insert_vmap_area(vas[area], &vn->busy.root, &vn->busy.head);
setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
setup_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
pcpu_get_vm_areas);
spin_unlock(&vn->busy.lock);
}