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> --- V1 -> V2: Avoided the partial initialization issue of vm and separated insert_vmap_area() from alloc_vmap_area() --- mm/vmalloc.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d12a17fc0c171..768e45f2ed946 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1630,17 +1630,18 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, va->vm = NULL; va->flags = va_flags; - spin_lock(&vmap_area_lock); - insert_vmap_area(va, &vmap_area_root, &vmap_area_list); - spin_unlock(&vmap_area_lock); - BUG_ON(!IS_ALIGNED(va->va_start, align)); BUG_ON(va->va_start < vstart); BUG_ON(va->va_end > vend); ret = kasan_populate_vmalloc(addr, size); if (ret) { - free_vmap_area(va); + /* + * Insert/Merge it back to the free tree/list. + */ + spin_lock(&free_vmap_area_lock); + merge_or_add_vmap_area_augment(va, &free_vmap_area_root, &free_vmap_area_list); + spin_unlock(&free_vmap_area_lock); return ERR_PTR(ret); } @@ -1669,6 +1670,13 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, return ERR_PTR(-EBUSY); } +static inline void insert_vmap_area_with_lock(struct vmap_area *va) +{ + spin_lock(&vmap_area_lock); + insert_vmap_area(va, &vmap_area_root, &vmap_area_list); + spin_unlock(&vmap_area_lock); +} + int register_vmap_purge_notifier(struct notifier_block *nb) { return blocking_notifier_chain_register(&vmap_notify_list, nb); @@ -2045,6 +2053,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) return ERR_CAST(va); } + insert_vmap_area_with_lock(va); + vaddr = vmap_block_vaddr(va->va_start, 0); spin_lock_init(&vb->lock); vb->va = va; @@ -2398,6 +2408,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) if (IS_ERR(va)) return NULL; + insert_vmap_area_with_lock(va); + addr = va->va_start; mem = (void *)addr; } @@ -2538,7 +2550,7 @@ static void vmap_init_free_space(void) } } -static inline void setup_vmalloc_vm_locked(struct vm_struct *vm, +static inline void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, unsigned long flags, const void *caller) { vm->flags = flags; @@ -2548,14 +2560,6 @@ 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) { /* @@ -2600,6 +2604,8 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, setup_vmalloc_vm(area, va, flags, caller); + insert_vmap_area_with_lock(va); + /* * 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. @@ -4166,7 +4172,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets, for (area = 0; area < nr_vms; area++) { insert_vmap_area(vas[area], &vmap_area_root, &vmap_area_list); - 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(&vmap_area_lock); base-commit: de927f6c0b07d9e698416c5b287c521b07694cac -- 2.43.0
