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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 77832C4338F for ; Thu, 5 Aug 2021 02:07:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 606B461078 for ; Thu, 5 Aug 2021 02:07:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238146AbhHECHx (ORCPT ); Wed, 4 Aug 2021 22:07:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:56902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238157AbhHECHx (ORCPT ); Wed, 4 Aug 2021 22:07:53 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 277146105A; Thu, 5 Aug 2021 02:07:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628129260; bh=FAgU+HEbsXK4K8T8RScmhBbTwiLIfjGq6BN9gfYg3hI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=rHK2xhsSc/oDlLVSZ8Ryhbhse8neBsYidP21souchjBdoVnDtCjZzbkNiOsoOv3f3 Jawle+/lG0GE9bdbyAZm666q/N82v60jb61a0v8f+MxpGpGuMX04En6b+pCxoFmc11 tUITYajXrqDeaE+bZ7u3IZTv1LgUo3EG/kovf7pdW1jGDvgs0p46toeNjcTKf+UI8v PDUzhVBx9f/Hn2rg/C3gNDxMghokw2yrLfRlavjRpnK6LswYUT4BJiV7Qb1DL2ICer Wc04mDhNVI7wKEltr9WY5nEw7mU5lIii36j8nhGkyQDGBJ+5y8yokz8EPlPuA3jksS /yvEZg+4eF5oA== Subject: [PATCH 14/14] xfs: throttle inode inactivation queuing on memory reclaim From: "Darrick J. Wong" To: djwong@kernel.org Cc: linux-xfs@vger.kernel.org, david@fromorbit.com, hch@infradead.org Date: Wed, 04 Aug 2021 19:07:39 -0700 Message-ID: <162812925986.2589546.10269888087074473602.stgit@magnolia> In-Reply-To: <162812918259.2589546.16599271324044986858.stgit@magnolia> References: <162812918259.2589546.16599271324044986858.stgit@magnolia> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Darrick J. Wong Now that we defer inode inactivation, we've decoupled the process of unlinking or closing an inode from the process of inactivating it. In theory this should lead to better throughput since we now inactivate the queued inodes in batches instead of one at a time. Unfortunately, one of the primary risks with this decoupling is the loss of rate control feedback between the frontend and background threads. In other words, a rm -rf /* thread can run the system out of memory if it can queue inodes for inactivation and jump to a new CPU faster than the background threads can actually clear the deferred work. The workers can get scheduled off the CPU if they have to do IO, etc. To solve this problem, we configure a shrinker so that it will activate the /second/ time the shrinkers are called. The custom shrinker will queue all percpu deferred inactivation workers immediately and set a flag to force frontend callers who are releasing a vfs inode to wait for the inactivation workers. On my test VM with 560M of RAM and a 2TB filesystem, this seems to solve most of the OOMing problem when deleting 10 million inodes. Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_icache.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++- fs/xfs/xfs_icache.h | 1 + fs/xfs/xfs_mount.c | 9 ++++- fs/xfs/xfs_mount.h | 3 ++ fs/xfs/xfs_trace.h | 37 ++++++++++++++++++- 5 files changed, 147 insertions(+), 5 deletions(-) diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index f5a4f4d64c50..6741e27603ad 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -1908,8 +1908,9 @@ xfs_inodegc_worker( return; ip = llist_entry(node, struct xfs_inode, i_gclist); - trace_xfs_inodegc_worker(ip->i_mount, __return_address); + trace_xfs_inodegc_worker(ip->i_mount, READ_ONCE(gc->shrinker_hits)); + WRITE_ONCE(gc->shrinker_hits, 0); llist_for_each_entry_safe(ip, n, node, i_gclist) { xfs_iflags_set(ip, XFS_INACTIVATING); xfs_inodegc_inactivate(ip); @@ -2046,13 +2047,18 @@ xfs_inodegc_want_queue_work( /* * Make the frontend wait for inactivations when: * + * - Memory shrinkers queued the inactivation worker and it hasn't finished. * - The queue depth exceeds the maximum allowable percpu backlog. */ static inline bool xfs_inodegc_want_flush_work( struct xfs_inode *ip, - unsigned int items) + unsigned int items, + unsigned int shrinker_hits) { + if (shrinker_hits > 0) + return true; + if (items > XFS_INODEGC_MAX_BACKLOG) return true; @@ -2071,6 +2077,7 @@ xfs_inodegc_queue( struct xfs_mount *mp = ip->i_mount; struct xfs_inodegc *gc; int items; + unsigned int shrinker_hits; trace_xfs_inode_set_need_inactive(ip); spin_lock(&ip->i_flags_lock); @@ -2081,6 +2088,7 @@ xfs_inodegc_queue( llist_add(&ip->i_gclist, &gc->list); items = READ_ONCE(gc->items); WRITE_ONCE(gc->items, items + 1); + shrinker_hits = READ_ONCE(gc->shrinker_hits); put_cpu_ptr(gc); if (!xfs_is_inodegc_enabled(mp)) @@ -2091,7 +2099,7 @@ xfs_inodegc_queue( queue_work(mp->m_inodegc_wq, &gc->work); } - if (xfs_inodegc_want_flush_work(ip, items)) { + if (xfs_inodegc_want_flush_work(ip, items, shrinker_hits)) { trace_xfs_inodegc_throttle(mp, __return_address); flush_work(&gc->work); } @@ -2169,3 +2177,91 @@ xfs_inode_mark_reclaimable( xfs_qm_dqdetach(ip); xfs_inodegc_set_reclaimable(ip); } + +/* + * Register a phony shrinker so that we can run background inodegc sooner when + * there's memory pressure. Inactivation does not itself free any memory but + * it does make inodes reclaimable, which eventually frees memory. + * + * The count function, seek value, and batch value are crafted to trigger the + * scan function during the second round of scanning. Hopefully this means + * that we reclaimed enough memory that initiating metadata transactions won't + * make things worse. + */ +#define XFS_INODEGC_SHRINKER_COUNT (1UL << DEF_PRIORITY) +#define XFS_INODEGC_SHRINKER_BATCH ((XFS_INODEGC_SHRINKER_COUNT / 2) + 1) + +static unsigned long +xfs_inodegc_shrinker_count( + struct shrinker *shrink, + struct shrink_control *sc) +{ + struct xfs_mount *mp = container_of(shrink, struct xfs_mount, + m_inodegc_shrinker); + struct xfs_inodegc *gc; + int cpu; + + if (!xfs_is_inodegc_enabled(mp)) + return 0; + + for_each_online_cpu(cpu) { + gc = per_cpu_ptr(mp->m_inodegc, cpu); + if (!llist_empty(&gc->list)) + return XFS_INODEGC_SHRINKER_COUNT; + } + + return 0; +} + +static unsigned long +xfs_inodegc_shrinker_scan( + struct shrinker *shrink, + struct shrink_control *sc) +{ + struct xfs_mount *mp = container_of(shrink, struct xfs_mount, + m_inodegc_shrinker); + struct xfs_inodegc *gc; + int cpu; + bool no_items = true; + + if (!xfs_is_inodegc_enabled(mp)) + return SHRINK_STOP; + + trace_xfs_inodegc_shrinker_scan(mp, sc, __return_address); + + for_each_online_cpu(cpu) { + gc = per_cpu_ptr(mp->m_inodegc, cpu); + if (!llist_empty(&gc->list)) { + unsigned int h = READ_ONCE(gc->shrinker_hits); + + WRITE_ONCE(gc->shrinker_hits, h + 1); + queue_work_on(cpu, mp->m_inodegc_wq, &gc->work); + no_items = false; + } + } + + /* + * If there are no inodes to inactivate, we don't want the shrinker + * to think there's deferred work to call us back about. + */ + if (no_items) + return LONG_MAX; + + return SHRINK_STOP; +} + +/* Register a shrinker so we can accelerate inodegc and throttle queuing. */ +int +xfs_inodegc_register_shrinker( + struct xfs_mount *mp) +{ + struct shrinker *shrink = &mp->m_inodegc_shrinker; + + shrink->count_objects = xfs_inodegc_shrinker_count; + shrink->scan_objects = xfs_inodegc_shrinker_scan; + shrink->seeks = 0; + shrink->flags = SHRINKER_NONSLAB; + shrink->batch = XFS_INODEGC_SHRINKER_BATCH; + + return register_shrinker(shrink); +} diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h index 18c2d224aa78..2e4cfddf8b8e 100644 --- a/fs/xfs/xfs_icache.h +++ b/fs/xfs/xfs_icache.h @@ -80,5 +80,6 @@ void xfs_inodegc_flush(struct xfs_mount *mp); void xfs_inodegc_stop(struct xfs_mount *mp); void xfs_inodegc_start(struct xfs_mount *mp); void xfs_inodegc_cpu_dead(struct xfs_mount *mp, unsigned int cpu); +int xfs_inodegc_register_shrinker(struct xfs_mount *mp); #endif diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index b81f2fc734bd..ff08192d8d2a 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -769,6 +769,10 @@ xfs_mountfs( goto out_free_perag; } + error = xfs_inodegc_register_shrinker(mp); + if (error) + goto out_fail_wait; + /* * Log's mount-time initialization. The first part of recovery can place * some items on the AIL, to be handled when recovery is finished or @@ -779,7 +783,7 @@ xfs_mountfs( XFS_FSB_TO_BB(mp, sbp->sb_logblocks)); if (error) { xfs_warn(mp, "log mount failed"); - goto out_fail_wait; + goto out_inodegc_shrinker; } /* Make sure the summary counts are ok. */ @@ -974,6 +978,8 @@ xfs_mountfs( xfs_unmount_flush_inodes(mp); out_log_dealloc: xfs_log_mount_cancel(mp); + out_inodegc_shrinker: + unregister_shrinker(&mp->m_inodegc_shrinker); out_fail_wait: if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp) xfs_buftarg_drain(mp->m_logdev_targp); @@ -1054,6 +1060,7 @@ xfs_unmountfs( #if defined(DEBUG) xfs_errortag_clearall(mp); #endif + unregister_shrinker(&mp->m_inodegc_shrinker); xfs_free_perag(mp); xfs_errortag_del(mp); diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h index 797b8068dfe6..3eb7b06f2eff 100644 --- a/fs/xfs/xfs_mount.h +++ b/fs/xfs/xfs_mount.h @@ -63,6 +63,7 @@ struct xfs_inodegc { struct llist_head list; struct work_struct work; unsigned int items; + unsigned int shrinker_hits; }; /* @@ -208,6 +209,8 @@ typedef struct xfs_mount { xfs_agnumber_t m_agirotor; /* last ag dir inode alloced */ spinlock_t m_agirotor_lock;/* .. and lock protecting it */ + /* Memory shrinker to throttle and reprioritize inodegc */ + struct shrinker m_inodegc_shrinker; /* * Workqueue item so that we can coalesce multiple inode flush attempts * into a single flush. diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index 0a179cfc35c0..90ae884bfee6 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -157,6 +157,22 @@ DEFINE_PERAG_REF_EVENT(xfs_perag_put); DEFINE_PERAG_REF_EVENT(xfs_perag_set_inode_tag); DEFINE_PERAG_REF_EVENT(xfs_perag_clear_inode_tag); +TRACE_EVENT(xfs_inodegc_worker, + TP_PROTO(struct xfs_mount *mp, unsigned int shrinker_hits), + TP_ARGS(mp, shrinker_hits), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(unsigned int, shrinker_hits) + ), + TP_fast_assign( + __entry->dev = mp->m_super->s_dev; + __entry->shrinker_hits = shrinker_hits; + ), + TP_printk("dev %d:%d shrinker_hits %u", + MAJOR(__entry->dev), MINOR(__entry->dev), + __entry->shrinker_hits) +); + #define XFS_STATE_FLAGS \ { (1UL << XFS_STATE_INODEGC_ENABLED), "inodegc" }, \ { (1UL << XFS_STATE_BLOCKGC_ENABLED), "blockgc" } @@ -195,7 +211,6 @@ DEFINE_EVENT(xfs_fs_class, name, \ DEFINE_FS_EVENT(xfs_inodegc_flush); DEFINE_FS_EVENT(xfs_inodegc_start); DEFINE_FS_EVENT(xfs_inodegc_stop); -DEFINE_FS_EVENT(xfs_inodegc_worker); DEFINE_FS_EVENT(xfs_inodegc_queue); DEFINE_FS_EVENT(xfs_inodegc_throttle); DEFINE_FS_EVENT(xfs_fs_sync_fs); @@ -204,6 +219,26 @@ DEFINE_FS_EVENT(xfs_blockgc_stop); DEFINE_FS_EVENT(xfs_blockgc_worker); DEFINE_FS_EVENT(xfs_blockgc_flush_all); +TRACE_EVENT(xfs_inodegc_shrinker_scan, + TP_PROTO(struct xfs_mount *mp, struct shrink_control *sc, + void *caller_ip), + TP_ARGS(mp, sc, caller_ip), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(unsigned long, nr_to_scan) + __field(void *, caller_ip) + ), + TP_fast_assign( + __entry->dev = mp->m_super->s_dev; + __entry->nr_to_scan = sc->nr_to_scan; + __entry->caller_ip = caller_ip; + ), + TP_printk("dev %d:%d nr_to_scan %lu caller %pS", + MAJOR(__entry->dev), MINOR(__entry->dev), + __entry->nr_to_scan, + __entry->caller_ip) +); + DECLARE_EVENT_CLASS(xfs_ag_class, TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno), TP_ARGS(mp, agno),