From nobody Sun Feb 8 16:05:24 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6AC6E4CE00 for ; Thu, 29 Feb 2024 08:26:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.7 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709195198; cv=none; b=lORfLT9SnR+lIfBP9fW0xQCzfdNvD3Wp7cNxu4NyFJ16lLmbdYbqd4JMlh1TPo1kGvGKEDXl7va56eXQknlECmC7iApSKI9+he4R7Gefol44j0/rlSRBUsSfT1PJGvPYoFwV+VvlXLSYLl2xD8IvZPghc08md9OAbFWkuIJA3yI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709195198; c=relaxed/simple; bh=juUcc4UcKK/NL61XUnA4t+5ff677KqidZ2CHwPWtVYc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hvWK4bytIVJy/KsJk3zLAYQtQQt14bIusYcGdMyMeDWcCAxMNIiobHtFvWUMuLFSxKjtSweTx7GP315Nm20vgxh1iQTfYMr3ZqsybdYJPkOUnnY9a8X1EPacKT9KiALsNCwOI6H+r592LfFasX7NKVwZMx4r4QJsYVdKwOd35a4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=nY9/lmKt; arc=none smtp.client-ip=192.198.163.7 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="nY9/lmKt" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709195196; x=1740731196; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=juUcc4UcKK/NL61XUnA4t+5ff677KqidZ2CHwPWtVYc=; b=nY9/lmKtN2mJm7OUgW9B5felRxxM+kkRVMH18cOxWdWkmQW2roldibY7 iZq59vTmq3ZejqR8/JbN2Njvv81ZgfkN7P0esAMIFBqKI5BlYgLZ9Q9KK hrp0dqzd8WmGZrF2J3BcWb5BByM6isVKXNYDLJXcHECurQM7grrbi6CVz m/ZQDceRrCEJqiPh/KkFbQSL7kHLjHwlBs43T/iNdQPD7gyh8PJELWwOh CLxgjFmf7QqRan/9MaQ1cxcVlN9QnWgdC/9w4EwpuUXyjfivK01KZ4RGI NRDmvWdVrPZOkpxDJcgGVKXyKVMbrSy+ZRi9l6npDlnQJ4obj30Ks9/2f A==; X-IronPort-AV: E=McAfee;i="6600,9927,10998"; a="29082088" X-IronPort-AV: E=Sophos;i="6.06,192,1705392000"; d="scan'208";a="29082088" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Feb 2024 00:26:34 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,192,1705392000"; d="scan'208";a="12360365" Received: from a4bf01946c30.jf.intel.com ([10.165.116.30]) by fmviesa004.fm.intel.com with ESMTP; 29 Feb 2024 00:26:33 -0800 From: rulinhuang To: urezki@gmail.com, bhe@redhat.com Cc: akpm@linux-foundation.org, colin.king@intel.com, hch@infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lstoakes@gmail.com, rulin.huang@intel.com, tianyou.li@intel.com, tim.c.chen@intel.com, wangyang.guo@intel.com, zhiguo.zhou@intel.com Subject: [PATCH v6] mm/vmalloc: lock contention optimization under multi-threading Date: Thu, 29 Feb 2024 00:26:11 -0800 Message-ID: <20240229082611.4104839-1-rulin.huang@intel.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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. Reviewed-by: Uladzislau Rezki Reviewed-by: Baoquan He Reviewed-by: "Chen, Tim C" Reviewed-by: "King, Colin" Signed-off-by: rulinhuang --- 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: cancel the split of alloc_vmap_area() and keep insert_vmap_area() V5 -> V6: add bug_on --- mm/vmalloc.c | 132 +++++++++++++++++++++++++-------------------------- 1 file changed, 64 insertions(+), 68 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 25a8df497255..5ae028b0d58d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1841,15 +1841,66 @@ node_alloc(unsigned long size, unsigned long align, return va; } =20 +/*** Per cpu kva allocator ***/ + +/* + * vmap space is limited especially on 32 bit architectures. Ensure there = is + * room for at least 16 percpu vmap blocks per CPU. + */ +/* + * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able + * to #define VMALLOC_SPACE (VMALLOC_END-VMALLOC_START). Guess + * instead (we just need a rough idea) + */ +#if BITS_PER_LONG =3D=3D 32 +#define VMALLOC_SPACE (128UL*1024*1024) +#else +#define VMALLOC_SPACE (128UL*1024*1024*1024) +#endif + +#define VMALLOC_PAGES (VMALLOC_SPACE / PAGE_SIZE) +#define VMAP_MAX_ALLOC BITS_PER_LONG /* 256K with 4K pages */ +#define VMAP_BBMAP_BITS_MAX 1024 /* 4MB with 4K pages */ +#define VMAP_BBMAP_BITS_MIN (VMAP_MAX_ALLOC*2) +#define VMAP_MIN(x, y) ((x) < (y) ? (x) : (y)) /* can't use min() */ +#define VMAP_MAX(x, y) ((x) > (y) ? (x) : (y)) /* can't use max() */ +#define VMAP_BBMAP_BITS \ + VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ + VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ + VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16)) + +#define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) + +/* + * Purge threshold to prevent overeager purging of fragmented blocks for + * regular operations: Purge if vb->free is less than 1/4 of the capacity. + */ +#define VMAP_PURGE_THRESHOLD (VMAP_BBMAP_BITS / 4) + +#define VMAP_RAM 0x1 /* indicates vm_map_ram area*/ +#define VMAP_BLOCK 0x2 /* mark out the vmap_block sub-type*/ +#define VMAP_FLAGS_MASK 0x3 + +static inline void setup_vmalloc_vm(struct vm_struct *vm, + struct vmap_area *va, unsigned long flags, const void *caller) +{ + vm->flags =3D flags; + vm->addr =3D (void *)va->va_start; + vm->size =3D va->va_end - va->va_start; + vm->caller =3D caller; + va->vm =3D 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; @@ -1912,6 +1963,11 @@ static struct vmap_area *alloc_vmap_area(unsigned lo= ng size, va->vm =3D NULL; va->flags =3D (va_flags | vn_id); =20 + if (vm) { + BUG_ON(va_flags & VMAP_RAM); + setup_vmalloc_vm(vm, va, flags, caller); + } + vn =3D addr_to_node(va->va_start); =20 spin_lock(&vn->busy.lock); @@ -2325,46 +2381,6 @@ static struct vmap_area *find_unlink_vmap_area(unsig= ned long addr) return NULL; } =20 -/*** Per cpu kva allocator ***/ - -/* - * vmap space is limited especially on 32 bit architectures. Ensure there = is - * room for at least 16 percpu vmap blocks per CPU. - */ -/* - * If we had a constant VMALLOC_START and VMALLOC_END, we'd like to be able - * to #define VMALLOC_SPACE (VMALLOC_END-VMALLOC_START). Guess - * instead (we just need a rough idea) - */ -#if BITS_PER_LONG =3D=3D 32 -#define VMALLOC_SPACE (128UL*1024*1024) -#else -#define VMALLOC_SPACE (128UL*1024*1024*1024) -#endif - -#define VMALLOC_PAGES (VMALLOC_SPACE / PAGE_SIZE) -#define VMAP_MAX_ALLOC BITS_PER_LONG /* 256K with 4K pages */ -#define VMAP_BBMAP_BITS_MAX 1024 /* 4MB with 4K pages */ -#define VMAP_BBMAP_BITS_MIN (VMAP_MAX_ALLOC*2) -#define VMAP_MIN(x, y) ((x) < (y) ? (x) : (y)) /* can't use min() */ -#define VMAP_MAX(x, y) ((x) > (y) ? (x) : (y)) /* can't use max() */ -#define VMAP_BBMAP_BITS \ - VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ - VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ - VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16)) - -#define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) - -/* - * Purge threshold to prevent overeager purging of fragmented blocks for - * regular operations: Purge if vb->free is less than 1/4 of the capacity. - */ -#define VMAP_PURGE_THRESHOLD (VMAP_BBMAP_BITS / 4) - -#define VMAP_RAM 0x1 /* indicates vm_map_ram area*/ -#define VMAP_BLOCK 0x2 /* mark out the vmap_block sub-type*/ -#define VMAP_FLAGS_MASK 0x3 - struct vmap_block_queue { spinlock_t lock; struct list_head free; @@ -2486,7 +2502,8 @@ static void *new_vmap_block(unsigned int order, gfp_t= gfp_mask) va =3D 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 co= unt, int node) struct vmap_area *va; va =3D 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; =20 @@ -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); } =20 -static inline void setup_vmalloc_vm_locked(struct vm_struct *vm, - struct vmap_area *va, unsigned long flags, const void *caller) -{ - vm->flags =3D flags; - vm->addr =3D (void *)va->va_start; - vm->size =3D va->va_end - va->va_start; - vm->caller =3D caller; - va->vm =3D vm; -} - -static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, - unsigned long flags, const void *caller) -{ - struct vmap_node *vn =3D 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(unsigne= d long size, if (!(flags & VM_NO_GUARD)) size +=3D PAGE_SIZE; =20 - va =3D alloc_vmap_area(size, align, start, end, node, gfp_mask, 0); + va =3D alloc_vmap_area(size, align, start, end, node, gfp_mask, 0, area, = flags, caller); if (IS_ERR(va)) { kfree(area); return NULL; } =20 - 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 l= ong *offsets, =20 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); } base-commit: 7e6ae2db7f319bf9613ec6db8fa3c9bc1de1b346 --=20 2.43.0