From patchwork Thu Aug 30 17:42:11 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josef Bacik X-Patchwork-Id: 10582465 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4BD8A5A4 for ; Thu, 30 Aug 2018 17:43:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 392BF284DA for ; Thu, 30 Aug 2018 17:43:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2BDAD28676; Thu, 30 Aug 2018 17:43:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C126C284DA for ; Thu, 30 Aug 2018 17:43:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727679AbeH3VqW (ORCPT ); Thu, 30 Aug 2018 17:46:22 -0400 Received: from mail-qt0-f193.google.com ([209.85.216.193]:45093 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726878AbeH3VqW (ORCPT ); Thu, 30 Aug 2018 17:46:22 -0400 Received: by mail-qt0-f193.google.com with SMTP id g44-v6so11258773qtb.12 for ; Thu, 30 Aug 2018 10:43:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=from:to:subject:date:message-id:in-reply-to:references; bh=NIWxUwG4u6mwzl5co7wrzycjU3C9VR1V8gjr46ELak0=; b=F3d1CObm5vzK3XFFdT+Z1FR7RGgxCyT21SHGloLi7qDINPsdgDpHiuFxhguW94u5H4 Wkx0U/9gU9Tx9GTOVbMomlR0kdITrWbeP/65fgaaVLyw1eZ6ZudxtAvl8Rl7/6o2XEA7 wXrbwx26Pcj5UffEr2RXB/neI6PiFa3le9l+O127pPP5dkBccKMD8DGENK3w3vfrqFKV 6HdsrRHQBNgwpTwzWOBGODN+CWVCpQZC85TMYcC2tZVcFyM0ttgVGurgGzhYPz45VqO2 1PpTVEBqobt2sg8zwLt+hSi4uv7lQz23GoIyj0OFJ44thhg4h9ULC2t8NIs0yHagu6Ce yeKw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references; bh=NIWxUwG4u6mwzl5co7wrzycjU3C9VR1V8gjr46ELak0=; b=Kn4Qf+vvcOS3vy84YwD44hBlvcVRW2AAJsLX4/8aZzbTqjcE+u65PgZdZLbmly+BHQ ZmRZ/KmnjAMxoOm2QjfUrQEXd1f1+37FHsFBsK7hAjt2dY6PMN0zTNVzQR71YVyUM5Xp OZN8U7kdK9uOAJjTOls7w56r8plEOOxla7/pvXaw4mHqh0U9c/qpgziejZKgkFhg6SD2 AiC+6CJOXFNmXaBlAfMhuGqMTSU+GjEXAtM13cKafCoqttPMG4xhVSQS/at3e3oUT7cK JtWx5xNw3QKi1XOBa0WnXpsUpA+VBZT72qo3MsQs7ZU0nkSkkK5nnzXW2iVSPHL0RT2q g0sw== X-Gm-Message-State: APzg51DeKBSogmh95dTn8TddicDZnLjvA1RViC/lqLPNxfY+Sev+25G5 2XrzvytYl2c/6v0/fw3ySLlScyAJh1+FQw== X-Google-Smtp-Source: ANB0Vdbupu8d2sfD8d+rPJbbfYN9k5juKNy2BF0qJQEBhLyzIfz2DvIzlo5U7VFoEYk/+x4mgNSLyw== X-Received: by 2002:a37:b842:: with SMTP id i63-v6mr11934670qkf.187.1535650986085; Thu, 30 Aug 2018 10:43:06 -0700 (PDT) Received: from localhost ([107.15.81.208]) by smtp.gmail.com with ESMTPSA id x46-v6sm4738923qtc.9.2018.08.30.10.43.04 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 30 Aug 2018 10:43:05 -0700 (PDT) From: Josef Bacik To: linux-btrfs@vger.kernel.org Subject: [PATCH 21/35] btrfs: only run delayed refs if we're committing Date: Thu, 30 Aug 2018 13:42:11 -0400 Message-Id: <20180830174225.2200-22-josef@toxicpanda.com> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180830174225.2200-1-josef@toxicpanda.com> References: <20180830174225.2200-1-josef@toxicpanda.com> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP I noticed in a giant dbench run that we spent a lot of time on lock contention while running transaction commit. This is because dbench results in a lot of fsync()'s that do a btrfs_transaction_commit(), and they all run the delayed refs first thing, so they all contend with each other. This leads to seconds of 0 throughput. Change this to only run the delayed refs if we're the ones committing the transaction. This makes the latency go away and we get no more lock contention. Signed-off-by: Josef Bacik Reviewed-by: Omar Sandoval --- fs/btrfs/transaction.c | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index ebb0c0405598..2bb19e2ded5e 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1918,15 +1918,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) btrfs_trans_release_metadata(trans); trans->block_rsv = NULL; - /* make a pass through all the delayed refs we have so far - * any runnings procs may add more while we are here - */ - ret = btrfs_run_delayed_refs(trans, 0); - if (ret) { - btrfs_end_transaction(trans); - return ret; - } - cur_trans = trans->transaction; /* @@ -1939,12 +1930,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) if (!list_empty(&trans->new_bgs)) btrfs_create_pending_block_groups(trans); - ret = btrfs_run_delayed_refs(trans, 0); - if (ret) { - btrfs_end_transaction(trans); - return ret; - } - if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) { int run_it = 0; @@ -2015,6 +2000,15 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) spin_unlock(&fs_info->trans_lock); } + /* + * We are now the only one in the commit area, we can run delayed refs + * without hitting a bunch of lock contention from a lot of people + * trying to commit the transaction at once. + */ + ret = btrfs_run_delayed_refs(trans, 0); + if (ret) + goto cleanup_transaction; + extwriter_counter_dec(cur_trans, trans->type); ret = btrfs_start_delalloc_flush(fs_info);