From nobody Sun Feb 8 02:55:54 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 A651045976 for ; Thu, 22 Feb 2024 12:04:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708603474; cv=none; b=RNoWOybFCj22pHf2BExwo7mMzv2/2aMJDWkjMQPFj+cNEapMZR8Tmwl7VpiGdNN2oAnuO0cU/xH8JxD2+4r3iqx7jDRKwrBRNTmR7/ukBdCIYeICOuhlINpD9WLlpnS+x1vPxiJ2s+PI+XqgIFGdg0odxTX9rmmLNmXbPqsg+e8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708603474; c=relaxed/simple; bh=bYSaX56dO8kdy94pHYYZFze3kwfrczgEVdVcwjZvFXk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WDT20IqDjR4eJRikjsEK+cGkTNTMTQfHQmjyLGHn7bHcpiQRbfgaNcWOhKNfXVos6xBteM0zZfMnZTOephZPvmZIbEbydCbWOrIzATJ5/hZ/GbKq3rz8dIJKAjBqm3WQWV21AJB6VcpHbmEkxOhzujOmVkMzo6a10obG7qupBJU= 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=JjvdF7qD; arc=none smtp.client-ip=192.198.163.12 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="JjvdF7qD" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708603473; x=1740139473; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=bYSaX56dO8kdy94pHYYZFze3kwfrczgEVdVcwjZvFXk=; b=JjvdF7qDG9ze+pq6VEJx+wl7rj9BW7LSBLQn/Extr5GF14y/QsTtcXzM x0+wJy1G4QMl66aaSljBUcbxpGBWakKFG2LQyaru9bez/TMC3XY8iwxu1 KurfvHu+jzlsoge/eh0T1w+mhGvQj87xto/+0RqMIb3UwYaW5WXREHjcp jjJt5ld4t3zgl4ionX+U151LDlrKYBuxzNxrsTYPtKAw1EZY5hTInQp2c 2PD+iQwSO0/QHP0DGKJ/zJbTVXuIO64SmO3y4WM6d1sXmDJs+i/n+dxgX jUliqN5uOz3WBARqU+0y/04ZuJ7nolK3df/jzrS+kIrb+1J1i0+s0wtpZ g==; X-IronPort-AV: E=McAfee;i="6600,9927,10991"; a="6600879" X-IronPort-AV: E=Sophos;i="6.06,177,1705392000"; d="scan'208";a="6600879" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Feb 2024 04:04:31 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10991"; a="913510455" X-IronPort-AV: E=Sophos;i="6.06,177,1705392000"; d="scan'208";a="913510455" Received: from linux-pnp-server-09.sh.intel.com ([10.239.176.190]) by fmsmga002.fm.intel.com with ESMTP; 22 Feb 2024 04:04:28 -0800 From: rulinhuang To: akpm@linux-foundation.org, urezki@gmail.com Cc: 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 v4] mm/vmalloc: lock contention optimization under multi-threading Date: Thu, 22 Feb 2024 07:05:36 -0500 Message-ID: <20240222120536.216166-1-rulin.huang@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240207033059.1565623-1-rulin.huang@intel.com> References: <20240207033059.1565623-1-rulin.huang@intel.com> 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_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 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 --- mm/vmalloc.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 25a8df497255..ce126e7bc3d8 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1851,7 +1851,6 @@ static struct vmap_area *alloc_vmap_area(unsigned lon= g size, int node, gfp_t gfp_mask, unsigned long va_flags) { - struct vmap_node *vn; struct vmap_area *va; unsigned long freed; unsigned long addr; @@ -1912,19 +1911,18 @@ static struct vmap_area *alloc_vmap_area(unsigned l= ong size, va->vm =3D NULL; va->flags =3D (va_flags | vn_id); =20 - vn =3D addr_to_node(va->va_start); - - spin_lock(&vn->busy.lock); - insert_vmap_area(va, &vn->busy.root, &vn->busy.head); - spin_unlock(&vn->busy.lock); - BUG_ON(!IS_ALIGNED(va->va_start, align)); BUG_ON(va->va_start < vstart); BUG_ON(va->va_end > vend); =20 ret =3D 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); } =20 @@ -1953,6 +1951,15 @@ static struct vmap_area *alloc_vmap_area(unsigned lo= ng size, return ERR_PTR(-EBUSY); } =20 +static inline void insert_vmap_area_locked(struct vmap_area *va) +{ + struct vmap_node *vn =3D addr_to_node(va->va_start); + + spin_lock(&vn->busy.lock); + insert_vmap_area(va, &vn->busy.root, &vn->busy.head); + spin_unlock(&vn->busy.lock); +} + int register_vmap_purge_notifier(struct notifier_block *nb) { return blocking_notifier_chain_register(&vmap_notify_list, nb); @@ -2492,6 +2499,8 @@ static void *new_vmap_block(unsigned int order, gfp_t= gfp_mask) return ERR_CAST(va); } =20 + insert_vmap_area_locked(va); + vaddr =3D vmap_block_vaddr(va->va_start, 0); spin_lock_init(&vb->lock); vb->va =3D va; @@ -2847,6 +2856,8 @@ void *vm_map_ram(struct page **pages, unsigned int co= unt, int node) if (IS_ERR(va)) return NULL; =20 + insert_vmap_area_locked(va); + addr =3D va->va_start; mem =3D (void *)addr; } @@ -2946,7 +2957,7 @@ 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, +static inline void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, unsigned long flags, const void *caller) { vm->flags =3D flags; @@ -2956,16 +2967,6 @@ static inline void setup_vmalloc_vm_locked(struct vm= _struct *vm, va->vm =3D vm; } =20 -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) { /* @@ -3010,6 +3011,8 @@ static struct vm_struct *__get_vm_area_node(unsigned = long size, =20 setup_vmalloc_vm(area, va, flags, caller); =20 + insert_vmap_area_locked(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. @@ -4584,7 +4587,7 @@ 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: 9d193b36872d153e02e80c26203de4ee15127b58 --=20 2.39.3