From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C13EC77B60 for ; Thu, 23 Mar 2023 19:21:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231758AbjCWTVz (ORCPT ); Thu, 23 Mar 2023 15:21:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229849AbjCWTVc (ORCPT ); Thu, 23 Mar 2023 15:21:32 -0400 Received: from mail-ed1-x533.google.com (mail-ed1-x533.google.com [IPv6:2a00:1450:4864:20::533]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A8CD2E188 for ; Thu, 23 Mar 2023 12:21:16 -0700 (PDT) Received: by mail-ed1-x533.google.com with SMTP id ew6so28201364edb.7 for ; Thu, 23 Mar 2023 12:21:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1679599275; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=5k6nQvr+OAnndWm5Fm48bRo3kejRzJbUnDprd7Qh5FQ=; b=IplSCuy7Ci5TZrXducJfaeYesnruom2cYs74x5WP9HCfDT57vEDfBVZ+X7NyH7j79W yXbmHDrP+L9GzimyTtFrzLuk9siC/JjDqQI6Ay1X1Y6M+mODmylo+0qejtICjEFW6nk7 VUBvyRC3fpFt5b3Jd705/z+DVOmq5LPVsjOo+/PK3QAn+nw7uwdIAdd9TnzNDGmwcr9S MEkRfubcyn9zr2ZuWBWRRaqOzXo6UlDfhd8QQeENDVsy+5AggNIxWAMwyTSwMhETLnen 9vc3NYu/hSohZV4N7Hifc6fv4Ap+t5/o44UV1Yw+D8k6CH0yBtJEaVAIC14F2vsp71FF H70A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679599275; 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=5k6nQvr+OAnndWm5Fm48bRo3kejRzJbUnDprd7Qh5FQ=; b=4F8tjgTsZu5d6nEq7ucU/kZFBOTfRqdvF/uOy7DL2iDwponUfNICWusMQcf4JRYle8 QcMNA8KHym4kv2uPTPXOZMG+KTr75rq65GsXhftT+cfiKnb+ZHEYBGR19EKUWV5naMfs as8HXn/M+QsLsiKxklOUO3UBwb2dTIuUQaJYjrZr6ESmK0atADaMLE+tZK8e7PSxrHqg UTULmrYJk7MwZIvwoMbyuTeK9ztRch4rkbUEdN27cdLVhKk17sbStO46LviC+bS70JXS 7ISjcv3nI31Gjd4cI5ziGFCXmOosIlM+g7+wW1ukMQSgHg0Jq0bDLWnSCsLx2RUJTJ0u DTlA== X-Gm-Message-State: AAQBX9clPNTm/MFxepkDYPp0Q3CrDSvrMYFiACKjfp7GKb1QBMtyVICe IPxeK/+4nUwrbfXdv12gCeo= X-Google-Smtp-Source: AKy350aT9RetWNYMtA/DMqLMcjWJycj9i8QSHZRi78UI2y3XtCDrFQeGuoiG9bJBi5veZc+ec4I+KA== X-Received: by 2002:a17:907:248c:b0:931:bbcf:eb6b with SMTP id zg12-20020a170907248c00b00931bbcfeb6bmr114330ejb.63.1679599274770; Thu, 23 Mar 2023 12:21:14 -0700 (PDT) Received: from pc638.lan ([155.137.26.201]) by smtp.gmail.com with ESMTPSA id lz24-20020a170906fb1800b009334309eda5sm7213127ejb.196.2023.03.23.12.21.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Mar 2023 12:21:14 -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 1/1] mm: vmalloc: Remove a global vmap_blocks xarray Date: Thu, 23 Mar 2023 20:21:11 +0100 Message-Id: <20230323192111.1501308-1-urezki@gmail.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Uladzislau Rezki (Sony) --- mm/vmalloc.c | 50 ++++++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 24 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 978194dc2bb8..13b5342bed9a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1911,6 +1911,7 @@ static struct vmap_area *find_unlink_vmap_area(unsigned long addr) struct vmap_block_queue { spinlock_t lock; struct list_head free; + struct xarray vmap_blocks; }; struct vmap_block { @@ -1927,25 +1928,18 @@ 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. - */ -static DEFINE_XARRAY(vmap_blocks); - -/* - * 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. - */ +static struct vmap_block_queue * +addr_to_vbq(unsigned long addr) +{ + int cpu = (addr / VMAP_BLOCK_SIZE) % num_possible_cpus(); + return &per_cpu(vmap_block_queue, cpu); +} -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; + /* A start address of block an address belongs to. */ + return rounddown(addr, VMAP_BLOCK_SIZE); } static void *vmap_block_vaddr(unsigned long va_start, unsigned long pages_off) @@ -1953,7 +1947,7 @@ 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)); + BUG_ON(addr_to_vb_va_start(addr) != addr_to_vb_va_start(va_start)); return (void *)addr; } @@ -1970,7 +1964,6 @@ 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 +1996,8 @@ 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 +2014,11 @@ 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 +2130,7 @@ 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 +2139,10 @@ 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 +3485,7 @@ 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 +3503,8 @@ 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 +4273,7 @@ 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. */ -- 2.30.2