From patchwork Mon Mar 27 16:52:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Uladzislau Rezki X-Patchwork-Id: 13189632 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A6D7C761A6 for ; Mon, 27 Mar 2023 16:52:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5EA08900004; Mon, 27 Mar 2023 12:52:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 54D0F900002; Mon, 27 Mar 2023 12:52:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3EC4E900004; Mon, 27 Mar 2023 12:52:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 2D402900002 for ; Mon, 27 Mar 2023 12:52:36 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 22FDB12088A for ; Mon, 27 Mar 2023 16:52:35 +0000 (UTC) X-FDA: 80615271870.01.ADE79FE Received: from mail-ed1-f54.google.com (mail-ed1-f54.google.com [209.85.208.54]) by imf04.hostedemail.com (Postfix) with ESMTP id 55CE440005 for ; Mon, 27 Mar 2023 16:52:32 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=JtE76LkX; spf=pass (imf04.hostedemail.com: domain of urezki@gmail.com designates 209.85.208.54 as permitted sender) smtp.mailfrom=urezki@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1679935952; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=HAyZ+gEgPpQPkbLRCxc/EE+kdr8FCKsyLZ7NAFDpy1Q=; b=0IO38Ogdf0vwxrH3FpljDLYaOoOcKcWBUQULAyEnizqShkVsSVzjCwd6FGw0GEJmB7sh1g dNZKto2ISQBzD6LPVisSYvPPXvVQ094j8UNGkUHRa3TPp0yAItDI4klfKk71rbLNkOyQck Zlev3Eku00RBLaapVDCDAyKo7fLpp0A= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=JtE76LkX; spf=pass (imf04.hostedemail.com: domain of urezki@gmail.com designates 209.85.208.54 as permitted sender) smtp.mailfrom=urezki@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1679935952; a=rsa-sha256; cv=none; b=szBLO0tjhTXpkIva1HQMiAOz7xmuwJBeVXrdAvdUuYweaI7HKOMypYK0QBUM3dnD3X1N/c UEc02Ntc1ujM4WSRgJ6JJ5KqIsoLKkq+OcQG066L2gspJ+4s1URwYCXnYdVMfDFufl5nXF TsCG9MP5Ca37OnHFg3GnuJQgaO9MM58= Received: by mail-ed1-f54.google.com with SMTP id i5so39086849eda.0 for ; Mon, 27 Mar 2023 09:52:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1679935950; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=HAyZ+gEgPpQPkbLRCxc/EE+kdr8FCKsyLZ7NAFDpy1Q=; b=JtE76LkX9IBS+/rANYNy3L4cwxHxK9ThiB7rbAFa7LAQwIXA3LNdt4zPW8yYl5tUR/ 7DwrXqTdzosq1DBo6pJSnpkaEk+onifwEZnCAo7zRbn+u8iicy1xW1D9algsH6k1Xjwm CYifF3bW1MLOmBEahhfry5Uxv3ZrEZJweOHcD9V0myfd8bayKlWiU34H067xD7jL3umg F27I78wu04ULE/4JInuXDMYH88vGPemaRHhV4buTImkjjwCT4xSc4k87EkpYy1cMjvzk GKcZG87KRC988CsUvG80+MDgNHDXh8qSX4zRpafdbQ7QylKiTqMjg1acHeSc6ToYScv5 1ZOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679935950; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=HAyZ+gEgPpQPkbLRCxc/EE+kdr8FCKsyLZ7NAFDpy1Q=; b=K3oBnNO0k41YLHfKunCWS0W/DEB9EKqpISjSPh9Z61GO+o8WM0gC/hO50gdjjcV3Ae jKb9r9+NLGH3nqO9bZdk6fWIkQ5PlDBe9QegJ2hEtIfeVdTmXLVm5ScTaDEwxeq5o0pH L0vXLStxGuEWgPEaDUqFUBXrB7YHRFhqIxXOfm3FXaLcxJGdxtMoK8z3mPBr9xzenT/d k44blUQ6FdQMBo0B1mGnG1MkUIy6G/QjxfnhyLkzPi89fZLyaMBcm1990/r6b5fpN5RZ E8Xk9apu6AFZjmLYfL3pG+Os09zp7WTBEMvqT2xuGwXTlIXWX1sKL39vTIkSRbejXh99 Z4Mw== X-Gm-Message-State: AAQBX9eQX0CxPilk49EcO6pm/w9CgmA5Eo/OjjaJOW3I6Dp6jciPZkY1 6ArfWzbmMbm0cTuDuf5TDco= X-Google-Smtp-Source: AKy350ao/WHhA01+gaptJojcbxp9T5t0WX558sNu3ZPQmsFwG6/WHqp76gdBjQBDlXG9PAqpSvenBQ== X-Received: by 2002:a17:907:98ce:b0:931:de86:1879 with SMTP id kd14-20020a17090798ce00b00931de861879mr14406636ejc.9.1679935950487; Mon, 27 Mar 2023 09:52:30 -0700 (PDT) Received: from pc638.lan ([155.137.26.201]) by smtp.gmail.com with ESMTPSA id b24-20020a170906491800b008e82cb55195sm14217282ejq.203.2023.03.27.09.52.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Mar 2023 09:52:30 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: Andrew Morton Cc: linux-mm@kvack.org, LKML , Baoquan He , Lorenzo Stoakes , Christoph Hellwig , Matthew Wilcox , Dave Chinner , Uladzislau Rezki , Oleksiy Avramchenko Subject: [PATCH v2 1/2] mm: vmalloc: Remove a global vmap_blocks xarray Date: Mon, 27 Mar 2023 18:52:26 +0200 Message-Id: <20230327165228.405045-1-urezki@gmail.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Stat-Signature: 4wfeaxk8jm3gke4s1ib5z6urcx4nb1cj X-Rspam-User: X-Rspamd-Queue-Id: 55CE440005 X-Rspamd-Server: rspam06 X-HE-Tag: 1679935952-926974 X-HE-Meta: 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 zVUEaBHE 91DESegQeyw/jPAPUrQbytRCl7GXm15HpRrSR8Eeqwhrs1d7UwFcAscIiaNEkHoJ8z96hVYHO+yC3CQfk6Z0fomOxxr2j8tnb+zGwUtgJnnKU89B/l9R7eQxYIglygavXMVOQl8dRTeXPD5toTuCCeLJmS2rZjP25F93l2/OGaWvumw+qZhNgv4Q719a5wgcdZuOdYMO3Ujae9vuiIyNrgl4pc0Feb3rW2ogMIoYZHo/XSqawPrwiqqITvqaLAg/Dmhv/Qf7FkUotKVFQHH/ChqcKWeCEL7av6PfAhjO5TZ2gkTQm/vr/XyLBmAr/W3qvVrDEG9MQp2ssTzpRxbgSyDinCbq7KcaqavSr/mvHa/4WMa4Q65Pe4hBbeHPcn39uwen4J5KpxtzMQye3LX7fsDMpgJhFkzycde6CNkp6OL1QNAl0BCFWBgBjzQu7TF1fAq5WC57qXdVQShnrUYC/LoCY2taz3v86iJWoUxVtcpgHra5B3YbtI+PLGD4RsT7Fzs29 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: A global vmap_blocks-xarray array can be contented under heavy usage of the vm_map_ram()/vm_unmap_ram() APIs. The lock_stat shows that a "vmap_blocks.xa_lock" lock is a second in a top-list when it comes to contentions: ---------------------------------------- class name con-bounces contentions ... ---------------------------------------- vmap_area_lock: 2554079 2554276 ... -------------- vmap_area_lock 1297948 [<00000000dd41cbaa>] alloc_vmap_area+0x1c7/0x910 vmap_area_lock 1256330 [<000000009d927bf3>] free_vmap_block+0x4a/0xe0 vmap_area_lock 1 [<00000000c95c05a7>] find_vm_area+0x16/0x70 -------------- vmap_area_lock 1738590 [<00000000dd41cbaa>] alloc_vmap_area+0x1c7/0x910 vmap_area_lock 815688 [<000000009d927bf3>] free_vmap_block+0x4a/0xe0 vmap_area_lock 1 [<00000000c1d619d7>] __get_vm_area_node+0xd2/0x170 vmap_blocks.xa_lock: 862689 862698 ... ------------------- vmap_blocks.xa_lock 378418 [<00000000625a5626>] vm_map_ram+0x359/0x4a0 vmap_blocks.xa_lock 484280 [<00000000caa2ef03>] xa_erase+0xe/0x30 ------------------- vmap_blocks.xa_lock 576226 [<00000000caa2ef03>] xa_erase+0xe/0x30 vmap_blocks.xa_lock 286472 [<00000000625a5626>] vm_map_ram+0x359/0x4a0 ... that is a result of running vm_map_ram()/vm_unmap_ram() in a loop. The test creates 64(on 64 CPUs system) threads and each one maps/unmaps 1 page. After this change the "xa_lock" can be considered as a noise in the same test condition: ... &xa->xa_lock#1: 10333 10394 ... -------------- &xa->xa_lock#1 5349 [<00000000bbbc9751>] xa_erase+0xe/0x30 &xa->xa_lock#1 5045 [<0000000018def45d>] vm_map_ram+0x3a4/0x4f0 -------------- &xa->xa_lock#1 7326 [<0000000018def45d>] vm_map_ram+0x3a4/0x4f0 &xa->xa_lock#1 3068 [<00000000bbbc9751>] xa_erase+0xe/0x30 ... This patch does not fix vmap_area_lock/free_vmap_area_lock and purge_vmap_area_lock bottle-necks, it is rather a separate rework. v1 - v2: - Add more comments(Andrew Morton req.) - Switch to WARN_ON_ONCE(Lorenzo Stoakes req.) Signed-off-by: Uladzislau Rezki (Sony) --- mm/vmalloc.c | 87 +++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 65 insertions(+), 22 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 978194dc2bb8..c0f5d87b154d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1908,9 +1908,22 @@ static struct vmap_area *find_unlink_vmap_area(unsigned long addr) #define VMAP_BLOCK 0x2 /* mark out the vmap_block sub-type*/ #define VMAP_FLAGS_MASK 0x3 +/* + * We should probably have a fallback mechanism to allocate virtual memory + * out of partially filled vmap blocks. However vmap block sizing should be + * fairly reasonable according to the vmalloc size, so it shouldn't be a + * big problem. + */ struct vmap_block_queue { spinlock_t lock; struct list_head free; + + /* + * An xarray requires an extra memory dynamically to + * be allocated. If it is an issue, we can use rb-tree + * instead. + */ + struct xarray vmap_blocks; }; struct vmap_block { @@ -1927,25 +1940,47 @@ struct vmap_block { /* Queue of free and dirty vmap blocks, for allocation and flushing purposes */ static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue); -/* - * XArray of vmap blocks, indexed by address, to quickly find a vmap block - * in the free path. Could get rid of this if we change the API to return a - * "cookie" from alloc, to be passed to free. But no big deal yet. +/** + * In order to fast access to any "vmap_block" associated with a + * specific address, we store them into a per-cpu xarray. A hash + * function is addr_to_vbq() whereas a key is a vb->va->va_start + * value. + * + * Please note, a vmap_block_queue, which is a per-cpu, is not + * serialized by a raw_smp_processor_id() current CPU, instead + * it is chosen based on a CPU-index it belongs to, i.e. it is + * a hash-table. + * + * An example: + * + * CPU_1 CPU_2 CPU_0 + * | | | + * V V V + * 0 10 20 30 40 50 60 + * |------|------|------|------|------|------|... + * CPU0 CPU1 CPU2 CPU0 CPU1 CPU2 + * + * - CPU_1 invokes vm_unmap_ram(6), 6 belongs to CPU0 zone, thus + * it access: CPU0/INDEX0 -> vmap_blocks -> xa_lock; + * + * - CPU_2 invokes vm_unmap_ram(11), 11 belongs to CPU1 zone, thus + * it access: CPU1/INDEX1 -> vmap_blocks -> xa_lock; + * + * - CPU_0 invokes vm_unmap_ram(20), 20 belongs to CPU2 zone, thus + * it access: CPU2/INDEX2 -> vmap_blocks -> xa_lock. */ -static DEFINE_XARRAY(vmap_blocks); +static struct vmap_block_queue * +addr_to_vbq(unsigned long addr) +{ + int index = (addr / VMAP_BLOCK_SIZE) % num_possible_cpus(); -/* - * We should probably have a fallback mechanism to allocate virtual memory - * out of partially filled vmap blocks. However vmap block sizing should be - * fairly reasonable according to the vmalloc size, so it shouldn't be a - * big problem. - */ + return &per_cpu(vmap_block_queue, index); +} -static unsigned long addr_to_vb_idx(unsigned long addr) +static unsigned long +addr_to_vb_va_start(unsigned long addr) { - addr -= VMALLOC_START & ~(VMAP_BLOCK_SIZE-1); - addr /= VMAP_BLOCK_SIZE; - return addr; + return rounddown(addr, VMAP_BLOCK_SIZE); } static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off) @@ -1953,7 +1988,7 @@ static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off) unsigned long addr; addr = va_start + (pages_off << PAGE_SHIFT); - BUG_ON(addr_to_vb_idx(addr) != addr_to_vb_idx(va_start)); + WARN_ON_ONCE(addr_to_vb_va_start(addr) != va_start); return (void *)addr; } @@ -1970,7 +2005,6 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) struct vmap_block_queue *vbq; struct vmap_block *vb; struct vmap_area *va; - unsigned long vb_idx; int node, err; void *vaddr; @@ -2003,8 +2037,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) bitmap_set(vb->used_map, 0, (1UL << order)); INIT_LIST_HEAD(&vb->free_list); - vb_idx = addr_to_vb_idx(va->va_start); - err = xa_insert(&vmap_blocks, vb_idx, vb, gfp_mask); + vbq = addr_to_vbq(va->va_start); + err = xa_insert(&vbq->vmap_blocks, va->va_start, vb, gfp_mask); if (err) { kfree(vb); free_vmap_area(va); @@ -2021,9 +2055,11 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask) static void free_vmap_block(struct vmap_block *vb) { + struct vmap_block_queue *vbq; struct vmap_block *tmp; - tmp = xa_erase(&vmap_blocks, addr_to_vb_idx(vb->va->va_start)); + vbq = addr_to_vbq(vb->va->va_start); + tmp = xa_erase(&vbq->vmap_blocks, vb->va->va_start); BUG_ON(tmp != vb); spin_lock(&vmap_area_lock); @@ -2135,6 +2171,7 @@ static void vb_free(unsigned long addr, unsigned long size) unsigned long offset; unsigned int order; struct vmap_block *vb; + struct vmap_block_queue *vbq; BUG_ON(offset_in_page(size)); BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC); @@ -2143,7 +2180,10 @@ static void vb_free(unsigned long addr, unsigned long size) order = get_order(size); offset = (addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT; - vb = xa_load(&vmap_blocks, addr_to_vb_idx(addr)); + + vbq = addr_to_vbq(addr); + vb = xa_load(&vbq->vmap_blocks, addr_to_vb_va_start(addr)); + spin_lock(&vb->lock); bitmap_clear(vb->used_map, offset, (1UL << order)); spin_unlock(&vb->lock); @@ -3486,6 +3526,7 @@ static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags { char *start; struct vmap_block *vb; + struct vmap_block_queue *vbq; unsigned long offset; unsigned int rs, re, n; @@ -3503,7 +3544,8 @@ static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags * Area is split into regions and tracked with vmap_block, read out * each region and zero fill the hole between regions. */ - vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); + vbq = addr_to_vbq((unsigned long) addr); + vb = xa_load(&vbq->vmap_blocks, addr_to_vb_va_start((unsigned long) addr)); if (!vb) goto finished; @@ -4272,6 +4314,7 @@ void __init vmalloc_init(void) p = &per_cpu(vfree_deferred, i); init_llist_head(&p->list); INIT_WORK(&p->wq, delayed_vfree_work); + xa_init(&vbq->vmap_blocks); } /* Import existing vmlist entries. */