From nobody Sun Feb 8 02:41:08 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 10E88101F2 for ; Wed, 7 Feb 2024 03:28:59 +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=1707276542; cv=none; b=VtNZtQd5Aep8ui/5x1TGEQJaYEOdzpY/+NHBvggKCSs89uw4FYZyAoXA4bGbV09nAVLcaQwiGs4Odg81DiNNMzhibRD8hroKw8XbcYGMncAfHKEfMmL44JQRASeGCQs2lSXNt7zx/y4WjMu4ck9hVYiRBM8VFK0OwLqdWypvFYM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707276542; c=relaxed/simple; bh=5z8kY6K3nvIR3A14IdHiEafFgYEBuUDMqEiZjPP8O+Y=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=HcXD0zRMQ+BTCznDwx4UMHB3a8sM7P0/Y4rDDHvzfyTE8TVoeUVtMbvfKlYUKZp7filFDasOtgfF7f6XeibwwmnbqYbW2MNNjVJWZ7uveJ2aDC0pz3VO6FAoH/RnGe8JPkPO/yF9LL+o6B2Se8qKn+OVL/bTem49CjR6j24M3UI= 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=IjBYdx31; 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="IjBYdx31" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1707276540; x=1738812540; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=5z8kY6K3nvIR3A14IdHiEafFgYEBuUDMqEiZjPP8O+Y=; b=IjBYdx31S828hlmx7Iv+rn38BUoJPFSrirsaMhWRpoRCOsFUqx+E+eOw cx26lSQfZdyQ+yBJYg9xSdjQIGaBej1/nlZ9PO9l0gIJ5BeZnLHVMn8al NPXs/CF879j3PjsKTF2M3QR2uwPFAzDimJAs+PGQcI1/nVzaT+frQD3uM mAzDTAVkFyN82VvpbZceiFE1stUsBkGMqSleOn/P3s7PWFN+sQGh/edbB 2vj1OdTcPi6wt8IjYgH/cd3KQmY5acsZrFpXooc46ER1/v0t1qR4+6PM7 8q+ML9wwENJ4Cy6sTVctcx5FyRLvKxEqF5CN3vp8v5Ev7zHLRzZR405os Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10976"; a="26344748" X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="26344748" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2024 19:28:55 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10976"; a="824384659" X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="824384659" Received: from linux-pnp-server-09.sh.intel.com ([10.239.176.190]) by orsmga001.jf.intel.com with ESMTP; 06 Feb 2024 19:28:52 -0800 From: rulinhuang To: akpm@linux-foundation.org Cc: urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, tim.c.chen@intel.com, colin.king@intel.com, zhiguo.zhou@intel.com, rulinhuang Subject: [PATCH] mm/vmalloc: lock contention optimization under multi-threading Date: Tue, 6 Feb 2024 22:30:59 -0500 Message-ID: <20240207033059.1565623-1-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_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 --- mm/vmalloc.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d12a17fc0c171..3b1f616e8ecf0 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1577,13 +1577,13 @@ preload_this_cpu_lock(spinlock_t *lock, gfp_t gfp_m= ask, int node) =20 /* * 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) { struct vmap_area *va; unsigned long freed; @@ -1627,9 +1627,12 @@ static struct vmap_area *alloc_vmap_area(unsigned lo= ng size, =20 va->va_start =3D addr; va->va_end =3D addr + size; - va->vm =3D NULL; + va->vm =3D vm; va->flags =3D va_flags; =20 + if (vm !=3D NULL) + vm->addr =3D (void *)addr; + spin_lock(&vmap_area_lock); insert_vmap_area(va, &vmap_area_root, &vmap_area_list); spin_unlock(&vmap_area_lock); @@ -2039,7 +2042,8 @@ 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); if (IS_ERR(va)) { kfree(vb); return ERR_CAST(va); @@ -2394,7 +2398,8 @@ 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); if (IS_ERR(va)) return NULL; =20 @@ -2548,14 +2553,6 @@ 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) -{ - 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) { /* @@ -2592,14 +2589,16 @@ 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); + area->flags =3D flags; + area->caller =3D caller; + area->size =3D size; + + va =3D alloc_vmap_area(size, align, start, end, node, gfp_mask, 0, area); 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. base-commit: de927f6c0b07d9e698416c5b287c521b07694cac --=20 2.43.0