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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53636C07E99 for ; Mon, 12 Jul 2021 15:40:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 397FF61222 for ; Mon, 12 Jul 2021 15:40:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235508AbhGLPnE (ORCPT ); Mon, 12 Jul 2021 11:43:04 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:42462 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234895AbhGLPnB (ORCPT ); Mon, 12 Jul 2021 11:43:01 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 47B641FFBE; Mon, 12 Jul 2021 15:40:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1626104412; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0eoYoqW5Z086PvZf45Mw/TzS7moHHtd7IKxhgJm6toc=; b=OKPBz0Y4O9F/hfyvEyMBe6azO3nRz7m28lTCHLplAVQDq7nRqJJP06uaF4s14WhdRaTQB+ ZaMltDVNEAIz+qZxSJ4B18XwZlbB1CnKgb1lkbT7b54VVt4HZuJyvpqO1UiE3SmIS4biFt 10bODsi/XnvjWk4xmzkDoEvJFd1K8k8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1626104412; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0eoYoqW5Z086PvZf45Mw/TzS7moHHtd7IKxhgJm6toc=; b=rVH0qwN20VHsdFr3ZscXhpZ6OHUVoVv7DpfJYZu7uok/LCxFBdDezh3kpI/D9doKNFjSfp oWfOrwJZI5cq+dAg== Received: from quack2.suse.cz (unknown [10.100.224.230]) by relay2.suse.de (Postfix) with ESMTP id 39E16A3B90; Mon, 12 Jul 2021 15:40:12 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 0A4AF1F2CD3; Mon, 12 Jul 2021 17:40:12 +0200 (CEST) From: Jan Kara To: Ted Tso Cc: , Jan Kara , Lukas Czerner Subject: [PATCH 5/5] ext4: Improve scalability of ext4 orphan file handling Date: Mon, 12 Jul 2021 17:40:09 +0200 Message-Id: <20210712154009.9290-6-jack@suse.cz> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210712154009.9290-1-jack@suse.cz> References: <20210712154009.9290-1-jack@suse.cz> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7858; h=from:subject; bh=Xwm4lVBXS4oUm74XybMn8JtmZR8nr9doGRLMnzJdPzQ=; b=owEBbQGS/pANAwAIAZydqgc/ZEDZAcsmYgBg7GJZXj5u0xj1Dnmk8s4s1aBNfiS54H5pYcxMUdcj I7TqEBuJATMEAAEIAB0WIQSrWdEr1p4yirVVKBycnaoHP2RA2QUCYOxiWQAKCRCcnaoHP2RA2Yg/CA CJEzf6f+MgfwfMXxKKdPqVeVQEi2oTP6HsvdMO+8Y/oTC6KxTlMaBMkAwNMoYQ9JloJUZKnD3CqE9b jCEC5YSOtjPQR5lvIPW3B8xuUhoC5wlHntYzLo/jfe7wQR0sGcdsdpODRoqrxt5afcSU4AJT1nbNCg fmmqRlkiUAJo57zbFCFQwXsWznObf0i4RO/ixBhgs281HLBOqMmkm3jaHWzdINLp9blou/S+c5UFuE BYmzuhYYUytW1SBxYgf/ecfFqlTYi20rK0KffLZmH9Ex/sclkpt4cq3OKZhrxV2ot3l+AV6SxynSyy mR2/dCxGFleQFF0LRXW//kW5Tex0XX X-Developer-Key: i=jack@suse.cz; a=openpgp; fpr=93C6099A142276A28BBE35D815BC833443038D8C Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Even though the length of the critical section when adding / removing orphaned inodes was significantly reduced by using orphan file, the contention of lock protecting orphan file still appears high in profiles for truncate / unlink intensive workloads with high number of threads. This patch makes handling of orphan file completely lockless. Also to reduce conflicts between CPUs different CPUs start searching for empty slot in orphan file in different blocks. Performance comparison of locked orphan file handling, lockless orphan file handling, and completely disabled orphan inode handling from 80 CPU Xeon Server with 526 GB of RAM, filesystem located on SAS SSD disk, average of 5 runs: stress-orphan (microbenchmark truncating files byte-by-byte from N processes in parallel) Threads Time Time Time Orphan locked Orphan lockless No orphan 1 0.945600 0.939400 0.891200 2 1.331800 1.246600 1.174400 4 1.995000 1.780600 1.713200 8 6.424200 4.900000 4.106000 16 14.937600 8.516400 8.138000 32 33.038200 24.565600 24.002200 64 60.823600 39.844600 38.440200 128 122.941400 70.950400 69.315000 So we can see that with lockless orphan file handling, addition / deletion of orphaned inodes got almost completely out of picture even for a microbenchmark stressing it. For reaim creat_clo workload on ramdisk there are also noticeable gains (average of 5 runs): Clients Vanilla (ops/s) Patched (ops/s) creat_clo-1 14705.88 ( 0.00%) 14354.07 * -2.39%* creat_clo-3 27108.43 ( 0.00%) 28301.89 ( 4.40%) creat_clo-5 37406.48 ( 0.00%) 45180.73 * 20.78%* creat_clo-7 41338.58 ( 0.00%) 54687.50 * 32.29%* creat_clo-9 45226.13 ( 0.00%) 62937.07 * 39.16%* creat_clo-11 44000.00 ( 0.00%) 65088.76 * 47.93%* creat_clo-13 36516.85 ( 0.00%) 68661.97 * 88.03%* creat_clo-15 30864.20 ( 0.00%) 69551.78 * 125.35%* creat_clo-17 27478.45 ( 0.00%) 67729.08 * 146.48%* creat_clo-19 25000.00 ( 0.00%) 61621.62 * 146.49%* creat_clo-21 18772.35 ( 0.00%) 63829.79 * 240.02%* creat_clo-23 16698.94 ( 0.00%) 61938.96 * 270.92%* creat_clo-25 14973.05 ( 0.00%) 56947.61 * 280.33%* creat_clo-27 16436.69 ( 0.00%) 65008.03 * 295.51%* creat_clo-29 13949.01 ( 0.00%) 69047.62 * 395.00%* creat_clo-31 14283.52 ( 0.00%) 67982.45 * 375.95%* Reviewed-by: Lukas Czerner Signed-off-by: Jan Kara --- fs/ext4/ext4.h | 3 +- fs/ext4/orphan.c | 72 ++++++++++++++++++++++++++++++++---------------- 2 files changed, 49 insertions(+), 26 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 83298c0b6dae..d08927e19b76 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1480,7 +1480,7 @@ static inline int ext4_inodes_per_orphan_block(struct super_block *sb) } struct ext4_orphan_block { - int ob_free_entries; /* Number of free orphan entries in block */ + atomic_t ob_free_entries; /* Number of free orphan entries in block */ struct buffer_head *ob_bh; /* Buffer for orphan block */ }; @@ -1488,7 +1488,6 @@ struct ext4_orphan_block { * Info about orphan file. */ struct ext4_orphan_info { - spinlock_t of_lock; int of_blocks; /* Number of orphan blocks in a file */ __u32 of_csum_seed; /* Checksum seed for orphan file */ struct ext4_orphan_block *of_binfo; /* Array with info about orphan diff --git a/fs/ext4/orphan.c b/fs/ext4/orphan.c index 95c2fa0e4e3e..da30bd68a760 100644 --- a/fs/ext4/orphan.c +++ b/fs/ext4/orphan.c @@ -10,16 +10,31 @@ static int ext4_orphan_file_add(handle_t *handle, struct inode *inode) { - int i, j; + int i, j, start; struct ext4_orphan_info *oi = &EXT4_SB(inode->i_sb)->s_orphan_info; int ret = 0; + bool found = false; __le32 *bdata; int inodes_per_ob = ext4_inodes_per_orphan_block(inode->i_sb); + int looped = 0; - spin_lock(&oi->of_lock); - for (i = 0; i < oi->of_blocks && !oi->of_binfo[i].ob_free_entries; i++); - if (i == oi->of_blocks) { - spin_unlock(&oi->of_lock); + /* + * Find block with free orphan entry. Use CPU number for a naive hash + * for a search start in the orphan file + */ + start = raw_smp_processor_id()*13 % oi->of_blocks; + i = start; + do { + if (atomic_dec_if_positive(&oi->of_binfo[i].ob_free_entries) + >= 0) { + found = true; + break; + } + if (++i >= oi->of_blocks) + i = 0; + } while (i != start); + + if (!found) { /* * For now we don't grow or shrink orphan file. We just use * whatever was allocated at mke2fs time. The additional @@ -28,28 +43,40 @@ static int ext4_orphan_file_add(handle_t *handle, struct inode *inode) */ return -ENOSPC; } - oi->of_binfo[i].ob_free_entries--; - spin_unlock(&oi->of_lock); - /* - * Get access to orphan block. We have dropped of_lock but since we - * have decremented number of free entries we are guaranteed free entry - * in our block. - */ ret = ext4_journal_get_write_access(handle, inode->i_sb, oi->of_binfo[i].ob_bh, EXT4_JTR_ORPHAN_FILE); if (ret) return ret; bdata = (__le32 *)(oi->of_binfo[i].ob_bh->b_data); - spin_lock(&oi->of_lock); /* Find empty slot in a block */ - for (j = 0; j < inodes_per_ob && bdata[j]; j++); - BUG_ON(j == inodes_per_ob); - bdata[j] = cpu_to_le32(inode->i_ino); + j = 0; + do { + if (looped) { + /* + * Did we walk through the block several times without + * finding free entry? It is theoretically possible + * if entries get constantly allocated and freed or + * if the block is corrupted. Avoid indefinite looping + * and bail. We'll use orphan list instead. + */ + if (looped > 3) { + atomic_inc(&oi->of_binfo[i].ob_free_entries); + return -ENOSPC; + } + cond_resched(); + } + while (bdata[j]) { + if (++j >= inodes_per_ob) { + j = 0; + looped++; + } + } + } while (cmpxchg(&bdata[j], 0, cpu_to_le32(inode->i_ino)) != 0); + EXT4_I(inode)->i_orphan_idx = i * inodes_per_ob + j; ext4_set_inode_state(inode, EXT4_STATE_ORPHAN_FILE); - spin_unlock(&oi->of_lock); return ext4_handle_dirty_metadata(handle, NULL, oi->of_binfo[i].ob_bh); } @@ -180,10 +207,8 @@ static int ext4_orphan_file_del(handle_t *handle, struct inode *inode) goto out; bdata = (__le32 *)(oi->of_binfo[blk].ob_bh->b_data); - spin_lock(&oi->of_lock); bdata[off] = 0; - oi->of_binfo[blk].ob_free_entries++; - spin_unlock(&oi->of_lock); + atomic_inc(&oi->of_binfo[blk].ob_free_entries); ret = ext4_handle_dirty_metadata(handle, NULL, oi->of_binfo[blk].ob_bh); out: ext4_clear_inode_state(inode, EXT4_STATE_ORPHAN_FILE); @@ -545,8 +570,6 @@ int ext4_init_orphan_info(struct super_block *sb) struct ext4_orphan_block_tail *ot; ino_t orphan_ino = le32_to_cpu(EXT4_SB(sb)->s_es->s_orphan_file_inum); - spin_lock_init(&oi->of_lock); - if (!ext4_has_feature_orphan_file(sb)) return 0; @@ -590,7 +613,7 @@ int ext4_init_orphan_info(struct super_block *sb) for (j = 0; j < inodes_per_ob; j++) if (bdata[j] == 0) free++; - oi->of_binfo[i].ob_free_entries = free; + atomic_set(&oi->of_binfo[i].ob_free_entries, free); } iput(inode); return 0; @@ -612,7 +635,8 @@ int ext4_orphan_file_empty(struct super_block *sb) if (!ext4_has_feature_orphan_file(sb)) return 1; for (i = 0; i < oi->of_blocks; i++) - if (oi->of_binfo[i].ob_free_entries != inodes_per_ob) + if (atomic_read(&oi->of_binfo[i].ob_free_entries) != + inodes_per_ob) return 0; return 1; } -- 2.26.2