From nobody Sun Feb 8 14:54:13 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (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 E3AB046AF for ; Thu, 7 Mar 2024 02:11:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709777496; cv=none; b=PkCC7t6cE+U9jNhaBugffowfuQxpRQCw56S8yTGwnX9LxuIDBPesJUa3ifbhSd//hDKLr3zbrRIkRWu4upItnPZul+zrk/ckcAdwlC4P46r1EyOh+/feyHWJwx0s7pMQtdkfTHDmpvbsesrOYcwVyTBQrcD1zf0Es0anmo0H5hw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709777496; c=relaxed/simple; bh=rSVzpqAtaP7VsIqGvDvnM7VnZ7HA9GL+hoNyerON4vw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=lQuvexJn1iXL748dag1DMbM/hoRSTs+K/TQZVCxU8R6avDyfd9Bhp67rvAK6XG0ypmM0uCYpdBOUbEbRWNFbI+mdwlgxb2sYuOj7/n+VK9ylrR5Vo3U/PZBeiqCZFxEVW0Jj3NTldP6k9eNZyweFY99L5CujZyk3pSrXh4x5lfE= 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=AqykEe/i; arc=none smtp.client-ip=192.198.163.15 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="AqykEe/i" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709777494; x=1741313494; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=rSVzpqAtaP7VsIqGvDvnM7VnZ7HA9GL+hoNyerON4vw=; b=AqykEe/iPYhB8PFnj1dpGbAt/D+WWQ+wH2GTC/25MF5xXg0RktWt2n5g 2g8CYXm/OX8cqz0Yh8PA2vnzmyf494Y4awL2WDR7KAqVg+mx6++p4UDM1 JxINoDeLhxSQj5sqZXWbZFRpT7uYWjavLQpjCd2z/xv+D0FkIDw0WkQ4H 5SRPk9kshwvcKWWaXrQ1QCFNtx/Wa+bKpN/peoB7AF6qYU1EFgy+Url+g 3OoUCTJMHVXkKVG206N+YykNEgdtyQCK2yq0JWyPl+zG2nvysVa0B7v/Z vKDN0I6UeTOqFsQGIsGoJzLknclh+JyVYz15fz9XqA4yeEM0KwLIGaNq+ g==; X-IronPort-AV: E=McAfee;i="6600,9927,11005"; a="4594949" X-IronPort-AV: E=Sophos;i="6.06,209,1705392000"; d="scan'208";a="4594949" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2024 18:11:33 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,209,1705392000"; d="scan'208";a="9852876" Received: from linux-pnp-server-09.sh.intel.com ([10.239.176.190]) by fmviesa007.fm.intel.com with ESMTP; 06 Mar 2024 18:11:30 -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 v8] mm/vmalloc: Eliminated the lock contention from twice to once Date: Wed, 6 Mar 2024 21:14:40 -0500 Message-ID: <20240307021440.64967-1-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. Co-developed-by: "Chen, Tim C" Signed-off-by: "Chen, Tim C" Co-developed-by: "King, Colin" Signed-off-by: "King, Colin" Signed-off-by: rulinhuang Reviewed-by: Baoquan He Reviewed-by: Uladzislau Rezki (Sony) --- 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 V7 -> V8: Removed bugs_on and adjustion of macros --- mm/vmalloc.c | 50 ++++++++++++++++++++++---------------------------- 1 file changed, 22 insertions(+), 28 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 25a8df497255..f933a62fef50 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1841,15 +1841,26 @@ node_alloc(unsigned long size, unsigned long align, return va; } =20 +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 +1923,9 @@ static struct vmap_area *alloc_vmap_area(unsigned lon= g size, va->vm =3D NULL; va->flags =3D (va_flags | vn_id); =20 + if (vm) + setup_vmalloc_vm(vm, va, flags, caller); + vn =3D addr_to_node(va->va_start); =20 spin_lock(&vn->busy.lock); @@ -2486,7 +2500,8 @@ 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 +2858,8 @@ 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 +2962,6 @@ 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 +2998,12 @@ 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 +4578,7 @@ 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: f4239a5d7acc1b5ff9bac4d5471000b952279ef0 --=20 2.43.0