When allocating a new memory area where the mapping address range is known, it is observed that the vmap_area 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_area lock is contended. By doing so, the need to acquire the lock twice can also be eliminated. With the above change, tested on intel icelake platform(160 vcpu, kernel v6.7), a 6% performance improvement and a 7% reduction in overall spinlock hotspot are gained on stress-ng/pthread(https://github.com/ColinIanKing/stress-ng), which is the stress test of thread creations. Reviewed-by: "Chen, Tim C" <tim.c.chen@xxxxxxxxx> Reviewed-by: "King, Colin" <colin.king@xxxxxxxxx> Signed-off-by: rulinhuang <rulin.huang@xxxxxxxxx> --- mm/vmalloc.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d12a17fc0c171..3b1f616e8ecf0 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1577,13 +1577,13 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_mask, int node) /* * 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) { struct vmap_area *va; unsigned long freed; @@ -1627,9 +1627,12 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, va->va_start = addr; va->va_end = addr + size; - va->vm = NULL; + va->vm = vm; va->flags = va_flags; + if (vm != NULL) + vm->addr = (void *)addr; + spin_lock(&vmap_area_lock); insert_vmap_area(va, &vmap_area_root, &vmap_area_list); spin_unlock(&vmap_area_lock); @@ -2039,7 +2042,8 @@ 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); if (IS_ERR(va)) { kfree(vb); return ERR_CAST(va); @@ -2394,7 +2398,8 @@ 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); if (IS_ERR(va)) return NULL; @@ -2548,14 +2553,6 @@ static inline void setup_vmalloc_vm_locked(struct vm_struct *vm, va->vm = vm; } -static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, - unsigned long flags, const void *caller) -{ - spin_lock(&vmap_area_lock); - setup_vmalloc_vm_locked(vm, va, flags, caller); - spin_unlock(&vmap_area_lock); -} - static void clear_vm_uninitialized_flag(struct vm_struct *vm) { /* @@ -2592,14 +2589,16 @@ 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); + area->flags = flags; + area->caller = caller; + area->size = size; + + va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0, area); 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. base-commit: de927f6c0b07d9e698416c5b287c521b07694cac -- 2.43.0
