From patchwork Wed Mar 6 14:53:28 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Mason X-Patchwork-Id: 2226481 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id A03A9DF23A for ; Wed, 6 Mar 2013 14:53:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758489Ab3CFOxc (ORCPT ); Wed, 6 Mar 2013 09:53:32 -0500 Received: from dkim2.fusionio.com ([66.114.96.54]:33947 "EHLO dkim2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757747Ab3CFOxb (ORCPT ); Wed, 6 Mar 2013 09:53:31 -0500 Received: from mx2.fusionio.com (unknown [10.101.1.160]) by dkim2.fusionio.com (Postfix) with ESMTP id E267C9A0368 for ; Wed, 6 Mar 2013 07:53:30 -0700 (MST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=fusionio.com; s=default; t=1362581610; bh=VOzZ4wGD4Z5i3OydUUR/zyoY2WLDdeJmfSOCYdecAB8=; h=Date:From:To:CC:Subject:References:In-Reply-To; b=q/UQgaIBCTcT7OeDFAuyFVooIDsGEzLXA9g21vDqhpsfiNijKE2Dq7kANtauEKA// kzdnzSqcQqMpJgmGYugvJoq2p9g5onHQgGLNuIXvKdeLzFNkxK9WdAJ3R+STJH+oC5 YtaQEvuzPKeMAhczrKerguTtSJMAaT5F2LC0D4ks= X-ASG-Debug-ID: 1362581610-0421b545491fc50001-6jHSXT Received: from mail1.int.fusionio.com (mail1.int.fusionio.com [10.101.1.21]) by mx2.fusionio.com with ESMTP id X3m7DuxkZoTysS28 (version=TLSv1 cipher=AES128-SHA bits=128 verify=NO); Wed, 06 Mar 2013 07:53:30 -0700 (MST) X-Barracuda-Envelope-From: clmason@fusionio.com Received: from localhost (67.247.72.189) by mail.fusionio.com (10.101.1.19) with Microsoft SMTP Server (TLS) id 8.3.83.0; Wed, 6 Mar 2013 07:53:29 -0700 Date: Wed, 6 Mar 2013 09:53:28 -0500 From: Chris Mason To: Miao Xie CC: Chris Mason , Linux Btrfs List Subject: Re: [PATCH] Btrfs: improve the delayed inode throttling Message-ID: <20130306145328.GE6904@shiny.masoncoding.com> X-ASG-Orig-Subj: Re: [PATCH] Btrfs: improve the delayed inode throttling Mail-Followup-To: Chris Mason , Miao Xie , Chris Mason , Linux Btrfs List References: <20130305154017.GF30680@shiny.masoncoding.com> <5136ADCE.9090405@cn.fujitsu.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5136ADCE.9090405@cn.fujitsu.com> User-Agent: Mutt/1.5.21 (2011-07-01) X-Barracuda-Connect: mail1.int.fusionio.com[10.101.1.21] X-Barracuda-Start-Time: 1362581610 X-Barracuda-Encrypted: AES128-SHA X-Barracuda-URL: http://10.101.1.181:8000/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at fusionio.com X-Barracuda-Spam-Score: 0.00 X-Barracuda-Spam-Status: No, SCORE=0.00 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.124424 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Mar 05, 2013 at 07:45:34PM -0700, Miao Xie wrote: > > We re-queue the node just when there are some delayed items in the current node. > But if the node still has delayed items after we deal with it, that is to say > someone is accessing the node. So it is better to release it and deal with it > later. In this way, we can amass more items and deal with them in batches. Thanks, I've made this change. > > > + } else { > > + btrfs_release_prepared_delayed_node(delayed_node); > > + if (async_work->nr == 0 || total_done < async_work->nr) > > + goto again; > > If joining transaction fails, we should end the async handle. And for case > ->nr == 0 (it means there are too many items, we need flush all), we can > set ->blocked of the current transaction, in this way, the users can not > insert any delayed item for a while, and will wait until the current > transation is committed This one I've left out for now, the old code didn't block and I'd prefer that we test that change independently. V2 below, it also has the break Liu Bo mentioned. From: Chris Mason Date: Mon, 4 Mar 2013 17:13:31 -0500 Subject: [PATCH] Btrfs: improve the delayed inode throttling The delayed inode code batches up changes to the btree in hopes of doing them in bulk. As the changes build up, processes kick off worker threads and wait for them to make progress. The current code kicks off an async work queue item for each delayed node, which creates a lot of churn. It also uses a fixed 1 HZ waiting period for the throttle, which allows us to build a lot of pending work and can slow down the commit. This changes us to watch a sequence counter as it is bumped during the operations. We kick off fewer work items and have each work item do more work. Signed-off-by: Chris Mason --- fs/btrfs/delayed-inode.c | 152 ++++++++++++++++++++++++++++------------------- fs/btrfs/delayed-inode.h | 2 + 2 files changed, 94 insertions(+), 60 deletions(-) diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c index 0b278b1..46f354a 100644 --- a/fs/btrfs/delayed-inode.c +++ b/fs/btrfs/delayed-inode.c @@ -22,8 +22,9 @@ #include "disk-io.h" #include "transaction.h" -#define BTRFS_DELAYED_WRITEBACK 400 -#define BTRFS_DELAYED_BACKGROUND 100 +#define BTRFS_DELAYED_WRITEBACK 512 +#define BTRFS_DELAYED_BACKGROUND 128 +#define BTRFS_DELAYED_BATCH 16 static struct kmem_cache *delayed_node_cache; @@ -494,6 +495,15 @@ static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node, BTRFS_DELAYED_DELETION_ITEM); } +static void finish_one_item(struct btrfs_delayed_root *delayed_root) +{ + int seq = atomic_inc_return(&delayed_root->items_seq); + if ((atomic_dec_return(&delayed_root->items) < + BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0) && + waitqueue_active(&delayed_root->wait)) + wake_up(&delayed_root->wait); +} + static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item) { struct rb_root *root; @@ -512,10 +522,8 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item) rb_erase(&delayed_item->rb_node, root); delayed_item->delayed_node->count--; - if (atomic_dec_return(&delayed_root->items) < - BTRFS_DELAYED_BACKGROUND && - waitqueue_active(&delayed_root->wait)) - wake_up(&delayed_root->wait); + + finish_one_item(delayed_root); } static void btrfs_release_delayed_item(struct btrfs_delayed_item *item) @@ -1056,10 +1064,7 @@ static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node) delayed_node->count--; delayed_root = delayed_node->root->fs_info->delayed_root; - if (atomic_dec_return(&delayed_root->items) < - BTRFS_DELAYED_BACKGROUND && - waitqueue_active(&delayed_root->wait)) - wake_up(&delayed_root->wait); + finish_one_item(delayed_root); } } @@ -1304,35 +1309,44 @@ void btrfs_remove_delayed_node(struct inode *inode) btrfs_release_delayed_node(delayed_node); } -struct btrfs_async_delayed_node { - struct btrfs_root *root; - struct btrfs_delayed_node *delayed_node; +struct btrfs_async_delayed_work { + struct btrfs_delayed_root *delayed_root; + int nr; struct btrfs_work work; }; -static void btrfs_async_run_delayed_node_done(struct btrfs_work *work) +static void btrfs_async_run_delayed_root(struct btrfs_work *work) { - struct btrfs_async_delayed_node *async_node; + struct btrfs_async_delayed_work *async_work; + struct btrfs_delayed_root *delayed_root; struct btrfs_trans_handle *trans; struct btrfs_path *path; struct btrfs_delayed_node *delayed_node = NULL; struct btrfs_root *root; struct btrfs_block_rsv *block_rsv; - int need_requeue = 0; + int total_done = 0; - async_node = container_of(work, struct btrfs_async_delayed_node, work); + async_work = container_of(work, struct btrfs_async_delayed_work, work); + delayed_root = async_work->delayed_root; path = btrfs_alloc_path(); if (!path) goto out; - path->leave_spinning = 1; - delayed_node = async_node->delayed_node; +again: + if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND / 2) + goto free_path; + + delayed_node = btrfs_first_prepared_delayed_node(delayed_root); + if (!delayed_node) + goto free_path; + + path->leave_spinning = 1; root = delayed_node->root; trans = btrfs_join_transaction(root); if (IS_ERR(trans)) - goto free_path; + goto release_path; block_rsv = trans->block_rsv; trans->block_rsv = &root->fs_info->delayed_block_rsv; @@ -1363,57 +1377,50 @@ static void btrfs_async_run_delayed_node_done(struct btrfs_work *work) * Task1 will sleep until the transaction is commited. */ mutex_lock(&delayed_node->mutex); - if (delayed_node->count) - need_requeue = 1; - else - btrfs_dequeue_delayed_node(root->fs_info->delayed_root, - delayed_node); + btrfs_dequeue_delayed_node(root->fs_info->delayed_root, delayed_node); mutex_unlock(&delayed_node->mutex); trans->block_rsv = block_rsv; btrfs_end_transaction_dmeta(trans, root); btrfs_btree_balance_dirty_nodelay(root); + +release_path: + btrfs_release_path(path); + total_done++; + + btrfs_release_prepared_delayed_node(delayed_node); + if (async_work->nr == 0 || total_done < async_work->nr) + goto again; + free_path: btrfs_free_path(path); out: - if (need_requeue) - btrfs_requeue_work(&async_node->work); - else { - btrfs_release_prepared_delayed_node(delayed_node); - kfree(async_node); - } + wake_up(&delayed_root->wait); + kfree(async_work); } + static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root, - struct btrfs_root *root, int all) + struct btrfs_root *root, int nr) { - struct btrfs_async_delayed_node *async_node; - struct btrfs_delayed_node *curr; - int count = 0; + struct btrfs_async_delayed_work *async_work; -again: - curr = btrfs_first_prepared_delayed_node(delayed_root); - if (!curr) + if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND) return 0; - async_node = kmalloc(sizeof(*async_node), GFP_NOFS); - if (!async_node) { - btrfs_release_prepared_delayed_node(curr); + async_work = kmalloc(sizeof(*async_work), GFP_NOFS); + if (!async_work) return -ENOMEM; - } - - async_node->root = root; - async_node->delayed_node = curr; - - async_node->work.func = btrfs_async_run_delayed_node_done; - async_node->work.flags = 0; - - btrfs_queue_worker(&root->fs_info->delayed_workers, &async_node->work); - count++; - if (all || count < 4) - goto again; + async_work->delayed_root = delayed_root; + async_work->work.func = btrfs_async_run_delayed_root; + async_work->work.flags = 0; + if (nr) + async_work->nr = 0; + else + async_work->nr = nr; + btrfs_queue_worker(&root->fs_info->delayed_workers, &async_work->work); return 0; } @@ -1424,30 +1431,55 @@ void btrfs_assert_delayed_root_empty(struct btrfs_root *root) WARN_ON(btrfs_first_delayed_node(delayed_root)); } +static int refs_newer(struct btrfs_delayed_root *delayed_root, + int seq, int count) +{ + int val = atomic_read(&delayed_root->items_seq); + + if (val < seq || val >= seq + count) + return 1; + return 0; +} + void btrfs_balance_delayed_items(struct btrfs_root *root) { struct btrfs_delayed_root *delayed_root; + int seq; delayed_root = btrfs_get_delayed_root(root); if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND) return; + seq = atomic_read(&delayed_root->items_seq); + if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) { int ret; + DEFINE_WAIT(__wait); + ret = btrfs_wq_run_delayed_node(delayed_root, root, 1); if (ret) return; - wait_event_interruptible_timeout( - delayed_root->wait, - (atomic_read(&delayed_root->items) < - BTRFS_DELAYED_BACKGROUND), - HZ); - return; + while (1) { + prepare_to_wait(&delayed_root->wait, &__wait, + TASK_INTERRUPTIBLE); + + if (refs_newer(delayed_root, seq, + BTRFS_DELAYED_BATCH) || + atomic_read(&delayed_root->items) < + BTRFS_DELAYED_BACKGROUND) { + break; + } + if (!signal_pending(current)) + schedule(); + else + break; + } + finish_wait(&delayed_root->wait, &__wait); } - btrfs_wq_run_delayed_node(delayed_root, root, 0); + btrfs_wq_run_delayed_node(delayed_root, root, BTRFS_DELAYED_BATCH); } /* Will return 0 or -ENOMEM */ diff --git a/fs/btrfs/delayed-inode.h b/fs/btrfs/delayed-inode.h index 78b6ad0..1d5c5f7 100644 --- a/fs/btrfs/delayed-inode.h +++ b/fs/btrfs/delayed-inode.h @@ -43,6 +43,7 @@ struct btrfs_delayed_root { */ struct list_head prepare_list; atomic_t items; /* for delayed items */ + atomic_t items_seq; /* for delayed items */ int nodes; /* for delayed nodes */ wait_queue_head_t wait; }; @@ -86,6 +87,7 @@ static inline void btrfs_init_delayed_root( struct btrfs_delayed_root *delayed_root) { atomic_set(&delayed_root->items, 0); + atomic_set(&delayed_root->items_seq, 0); delayed_root->nodes = 0; spin_lock_init(&delayed_root->lock); init_waitqueue_head(&delayed_root->wait);