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Message-ID: <20240301155417.1852290-3-rulin.huang@intel.com>
Date: Fri, 1 Mar 2024 10:54:17 -0500
From: rulinhuang <rulin.huang@...el.com>
To: urezki@...il.com,
bhe@...hat.com
Cc: akpm@...ux-foundation.org,
colin.king@...el.com,
hch@...radead.org,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
lstoakes@...il.com,
rulin.huang@...el.com,
tianyou.li@...el.com,
tim.c.chen@...el.com,
wangyang.guo@...el.com,
zhiguo.zhou@...el.com
Subject: [PATCH v7 2/2] mm/vmalloc: Eliminated the lock contention from twice to once
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.
Co-developed-by: "Chen, Tim C" <tim.c.chen@...el.com>
Signed-off-by: "Chen, Tim C" <tim.c.chen@...el.com>
Co-developed-by: "King, Colin" <colin.king@...el.com>
Signed-off-by: "King, Colin" <colin.king@...el.com>
Signed-off-by: rulinhuang <rulin.huang@...el.com>
---
V1 -> V2: Avoided the partial initialization issue of vm and
separated insert_vmap_area() from alloc_vmap_area()
V2 -> V3: Rebased on 6.8-rc5
V3 -> V4: Rebased on mm-unstable branch
V4 -> V5: Canceled the split of alloc_vmap_area()
and keep insert_vmap_area()
V5 -> V6: Added bug_on
V6 -> V7: Adjusted the macros
---
mm/vmalloc.c | 52 ++++++++++++++++++++++++----------------------------
1 file changed, 24 insertions(+), 28 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index fc027a61c12e..5b7c9156d8da 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1972,15 +1972,26 @@ 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;
@@ -2043,6 +2054,11 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
va->vm = NULL;
va->flags = (va_flags | vn_id);
+ if (vm) {
+ BUG_ON(va_flags & VMAP_RAM);
+ setup_vmalloc_vm(vm, va, flags, caller);
+ }
+
vn = addr_to_node(va->va_start);
spin_lock(&vn->busy.lock);
@@ -2486,7 +2502,8 @@ 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);
@@ -2843,7 +2860,8 @@ 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;
@@ -2946,26 +2964,6 @@ 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)
{
/*
@@ -3002,14 +3000,12 @@ 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.
@@ -4584,7 +4580,7 @@ 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);
}
--
2.43.0
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