From nobody Sat Feb 7 11:38:10 2026 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.16]) (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 8B6FD38F84 for ; Wed, 21 Feb 2024 03:26:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708486003; cv=none; b=iSC3669MywiXgPXXuzglONG/oLTdlj2gK66Rf9KWzP5FyndCa3oPAICPdT4BeV7/aBXqkSb3ULugmgSjizBIuEyQxClyjE4UBxUts240aMPY0TTHVWD3emQfkEuULePEfBGtNCgGmUb04XxiDv691jd9pRWzCE7oQX8lOvWq2Tw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708486003; c=relaxed/simple; bh=DRLcudGaxUx+pa5ipV8atxZFzPwCvpE7YqFV5CEEaes=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lbkpm1OKE9L6rjjXXq9e3+TBlmwaiD+ccNBeWOa3zkIwTfNy2DqGHmxvYnUYmzp0ZD8pHF3R7MSFYVqam6R0Kj39vfFN6+Sac7Kek9tajxxKjuFSyOpwuCwYD3r13KwcNs4ZoKGSeovg2q+l9Q3MTL26ZwZaAyQHainTkVUGyM0= 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=iiGvafdM; arc=none smtp.client-ip=192.198.163.16 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="iiGvafdM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708485995; x=1740021995; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DRLcudGaxUx+pa5ipV8atxZFzPwCvpE7YqFV5CEEaes=; b=iiGvafdMB0cdSSB7qltxws00WUSJKzs/p/goKDPc4nDm4wFGBcRDAbXh pEwO//R2eEiZ7UoNr30C1eaBO+FRRZ4RbcJbYxVgvpehwaP+XQSZsJ1mb rSKH9OZwPO1DS8r6WODtLwybyBVouZRo6GwUVPRAGWaWS2hUinldYrC5s uy2jyYIt17nOp8UIwvpUJ5gOtkSaJ0WshKESySjpPs1cF9Yzhlm/vefdX BSNjvrqcraNR1gzVPQPWHJ5CDGGcSy0q+JQkmj+0q1g8AH87BqNv+V68t SE13z1Z6Q4zEa7Kogw+B9bUIpQF9kJoYL+UJ6Ja4pFlrQNKYdKSQlJ2Ys g==; X-IronPort-AV: E=McAfee;i="6600,9927,10990"; a="3104520" X-IronPort-AV: E=Sophos;i="6.06,174,1705392000"; d="scan'208";a="3104520" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Feb 2024 19:26:32 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,174,1705392000"; d="scan'208";a="4935110" Received: from linux-pnp-server-09.sh.intel.com ([10.239.176.190]) by orviesa009.jf.intel.com with ESMTP; 20 Feb 2024 19:26:29 -0800 From: rulinhuang To: akpm@linux-foundation.org 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, urezki@gmail.com, wangyang.guo@intel.com, zhiguo.zhou@intel.com Subject: [PATCH v3] mm/vmalloc: lock contention optimization under multi-threading Date: Tue, 20 Feb 2024 22:29:05 -0500 Message-ID: <20240221032905.11392-1-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=20 separated insert_vmap_area() from alloc_vmap_area() V2 -> V3: Rebased on 6.8-rc5 --- mm/vmalloc.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d12a17fc0c17..768e45f2ed94 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1630,17 +1630,18 @@ static struct vmap_area *alloc_vmap_area(unsigned l= ong size, va->vm =3D NULL; va->flags =3D va_flags; =20 - spin_lock(&vmap_area_lock); - insert_vmap_area(va, &vmap_area_root, &vmap_area_list); - spin_unlock(&vmap_area_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 @@ -1669,6 +1670,13 @@ static struct vmap_area *alloc_vmap_area(unsigned lo= ng size, return ERR_PTR(-EBUSY); } =20 +static inline void insert_vmap_area_with_lock(struct vmap_area *va) +{ + spin_lock(&vmap_area_lock); + insert_vmap_area(va, &vmap_area_root, &vmap_area_list); + spin_unlock(&vmap_area_lock); +} + int register_vmap_purge_notifier(struct notifier_block *nb) { return blocking_notifier_chain_register(&vmap_notify_list, nb); @@ -2045,6 +2053,8 @@ static void *new_vmap_block(unsigned int order, gfp_t= gfp_mask) return ERR_CAST(va); } =20 + insert_vmap_area_with_lock(va); + vaddr =3D vmap_block_vaddr(va->va_start, 0); spin_lock_init(&vb->lock); vb->va =3D va; @@ -2398,6 +2408,8 @@ void *vm_map_ram(struct page **pages, unsigned int co= unt, int node) if (IS_ERR(va)) return NULL; =20 + insert_vmap_area_with_lock(va); + addr =3D va->va_start; mem =3D (void *)addr; } @@ -2538,7 +2550,7 @@ static void vmap_init_free_space(void) } } =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; @@ -2548,14 +2560,6 @@ 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) { /* @@ -2600,6 +2604,8 @@ static struct vm_struct *__get_vm_area_node(unsigned = long size, =20 setup_vmalloc_vm(area, va, flags, caller); =20 + insert_vmap_area_with_lock(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. @@ -4166,7 +4172,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned l= ong *offsets, for (area =3D 0; area < nr_vms; area++) { insert_vmap_area(vas[area], &vmap_area_root, &vmap_area_list); =20 - 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(&vmap_area_lock); base-commit: b401b621758e46812da61fa58a67c3fd8d91de0d --=20 2.43.0