From patchwork Thu Oct 31 23:45:57 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Chinner X-Patchwork-Id: 11222207 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 24AAC13BD for ; Thu, 31 Oct 2019 23:48:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D0DE218AC for ; Thu, 31 Oct 2019 23:48:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728528AbfJaXq2 (ORCPT ); Thu, 31 Oct 2019 19:46:28 -0400 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:55491 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728307AbfJaXq1 (ORCPT ); Thu, 31 Oct 2019 19:46:27 -0400 Received: from dread.disaster.area (pa49-180-67-183.pa.nsw.optusnet.com.au [49.180.67.183]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 9459C3A23D0; Fri, 1 Nov 2019 10:46:20 +1100 (AEDT) Received: from discord.disaster.area ([192.168.253.110]) by dread.disaster.area with esmtp (Exim 4.92.3) (envelope-from ) id 1iQK8x-0007C8-7k; Fri, 01 Nov 2019 10:46:19 +1100 Received: from dave by discord.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1iQK8x-00041U-51; Fri, 01 Nov 2019 10:46:19 +1100 From: Dave Chinner To: linux-xfs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 07/28] xfs: tail updates only need to occur when LSN changes Date: Fri, 1 Nov 2019 10:45:57 +1100 Message-Id: <20191031234618.15403-8-david@fromorbit.com> X-Mailer: git-send-email 2.24.0.rc0 In-Reply-To: <20191031234618.15403-1-david@fromorbit.com> References: <20191031234618.15403-1-david@fromorbit.com> MIME-Version: 1.0 X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=P6RKvmIu c=1 sm=1 tr=0 a=3wLbm4YUAFX2xaPZIabsgw==:117 a=3wLbm4YUAFX2xaPZIabsgw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=MeAgGD-zjQ4A:10 a=20KFwNOVAAAA:8 a=W3SVq3cs_kfo-QxLsoMA:9 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Dave Chinner We currently wake anything waiting on the log tail to move whenever the log item at the tail of the log is removed. Historically this was fine behaviour because there were very few items at any given LSN. But with delayed logging, there may be thousands of items at any given LSN, and we can't move the tail until they are all gone. Hence if we are removing them in near tail-first order, we might be waking up processes waiting on the tail LSN to change (e.g. log space waiters) repeatedly without them being able to make progress. This also occurs with the new sync push waiters, and can result in thousands of spurious wakeups every second when under heavy direct reclaim pressure. To fix this, check that the tail LSN has actually changed on the AIL before triggering wakeups. This will reduce the number of spurious wakeups when doing bulk AIL removal and make this code much more efficient. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Brian Foster Reviewed-by: Darrick J. Wong --- fs/xfs/xfs_inode_item.c | 18 ++++++++++---- fs/xfs/xfs_trans_ail.c | 52 ++++++++++++++++++++++++++++------------- fs/xfs/xfs_trans_priv.h | 4 ++-- 3 files changed, 51 insertions(+), 23 deletions(-) diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c index ab12e526540a..79ffe6dff115 100644 --- a/fs/xfs/xfs_inode_item.c +++ b/fs/xfs/xfs_inode_item.c @@ -731,19 +731,27 @@ xfs_iflush_done( * holding the lock before removing the inode from the AIL. */ if (need_ail) { - bool mlip_changed = false; + xfs_lsn_t tail_lsn = 0; /* this is an opencoded batch version of xfs_trans_ail_delete */ spin_lock(&ailp->ail_lock); list_for_each_entry(blip, &tmp, li_bio_list) { if (INODE_ITEM(blip)->ili_logged && - blip->li_lsn == INODE_ITEM(blip)->ili_flush_lsn) - mlip_changed |= xfs_ail_delete_one(ailp, blip); - else { + blip->li_lsn == INODE_ITEM(blip)->ili_flush_lsn) { + /* + * xfs_ail_update_finish() only cares about the + * lsn of the first tail item removed, any + * others will be at the same or higher lsn so + * we just ignore them. + */ + xfs_lsn_t lsn = xfs_ail_delete_one(ailp, blip); + if (!tail_lsn && lsn) + tail_lsn = lsn; + } else { xfs_clear_li_failed(blip); } } - xfs_ail_update_finish(ailp, mlip_changed); + xfs_ail_update_finish(ailp, tail_lsn); } /* diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c index 656819523bbd..685a21cd24c0 100644 --- a/fs/xfs/xfs_trans_ail.c +++ b/fs/xfs/xfs_trans_ail.c @@ -108,17 +108,25 @@ xfs_ail_next( * We need the AIL lock in order to get a coherent read of the lsn of the last * item in the AIL. */ +static xfs_lsn_t +__xfs_ail_min_lsn( + struct xfs_ail *ailp) +{ + struct xfs_log_item *lip = xfs_ail_min(ailp); + + if (lip) + return lip->li_lsn; + return 0; +} + xfs_lsn_t xfs_ail_min_lsn( struct xfs_ail *ailp) { - xfs_lsn_t lsn = 0; - struct xfs_log_item *lip; + xfs_lsn_t lsn; spin_lock(&ailp->ail_lock); - lip = xfs_ail_min(ailp); - if (lip) - lsn = lip->li_lsn; + lsn = __xfs_ail_min_lsn(ailp); spin_unlock(&ailp->ail_lock); return lsn; @@ -681,11 +689,12 @@ xfs_ail_push_all_sync( void xfs_ail_update_finish( struct xfs_ail *ailp, - bool do_tail_update) __releases(ailp->ail_lock) + xfs_lsn_t old_lsn) __releases(ailp->ail_lock) { struct xfs_mount *mp = ailp->ail_mount; - if (!do_tail_update) { + /* if the tail lsn hasn't changed, don't do updates or wakeups. */ + if (!old_lsn || old_lsn == __xfs_ail_min_lsn(ailp)) { spin_unlock(&ailp->ail_lock); return; } @@ -730,7 +739,7 @@ xfs_trans_ail_update_bulk( xfs_lsn_t lsn) __releases(ailp->ail_lock) { struct xfs_log_item *mlip; - int mlip_changed = 0; + xfs_lsn_t tail_lsn = 0; int i; LIST_HEAD(tmp); @@ -745,9 +754,10 @@ xfs_trans_ail_update_bulk( continue; trace_xfs_ail_move(lip, lip->li_lsn, lsn); + if (mlip == lip && !tail_lsn) + tail_lsn = lip->li_lsn; + xfs_ail_delete(ailp, lip); - if (mlip == lip) - mlip_changed = 1; } else { trace_xfs_ail_insert(lip, 0, lsn); } @@ -758,15 +768,23 @@ xfs_trans_ail_update_bulk( if (!list_empty(&tmp)) xfs_ail_splice(ailp, cur, &tmp, lsn); - xfs_ail_update_finish(ailp, mlip_changed); + xfs_ail_update_finish(ailp, tail_lsn); } -bool +/* + * Delete one log item from the AIL. + * + * If this item was at the tail of the AIL, return the LSN of the log item so + * that we can use it to check if the LSN of the tail of the log has moved + * when finishing up the AIL delete process in xfs_ail_update_finish(). + */ +xfs_lsn_t xfs_ail_delete_one( struct xfs_ail *ailp, struct xfs_log_item *lip) { struct xfs_log_item *mlip = xfs_ail_min(ailp); + xfs_lsn_t lsn = lip->li_lsn; trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn); xfs_ail_delete(ailp, lip); @@ -774,7 +792,9 @@ xfs_ail_delete_one( clear_bit(XFS_LI_IN_AIL, &lip->li_flags); lip->li_lsn = 0; - return mlip == lip; + if (mlip == lip) + return lsn; + return 0; } /** @@ -805,7 +825,7 @@ xfs_trans_ail_delete( int shutdown_type) { struct xfs_mount *mp = ailp->ail_mount; - bool need_update; + xfs_lsn_t tail_lsn; if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) { spin_unlock(&ailp->ail_lock); @@ -818,8 +838,8 @@ xfs_trans_ail_delete( return; } - need_update = xfs_ail_delete_one(ailp, lip); - xfs_ail_update_finish(ailp, need_update); + tail_lsn = xfs_ail_delete_one(ailp, lip); + xfs_ail_update_finish(ailp, tail_lsn); } int diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h index 64ffa746730e..35655eac01a6 100644 --- a/fs/xfs/xfs_trans_priv.h +++ b/fs/xfs/xfs_trans_priv.h @@ -91,8 +91,8 @@ xfs_trans_ail_update( xfs_trans_ail_update_bulk(ailp, NULL, &lip, 1, lsn); } -bool xfs_ail_delete_one(struct xfs_ail *ailp, struct xfs_log_item *lip); -void xfs_ail_update_finish(struct xfs_ail *ailp, bool do_tail_update) +xfs_lsn_t xfs_ail_delete_one(struct xfs_ail *ailp, struct xfs_log_item *lip); +void xfs_ail_update_finish(struct xfs_ail *ailp, xfs_lsn_t old_lsn) __releases(ailp->ail_lock); void xfs_trans_ail_delete(struct xfs_ail *ailp, struct xfs_log_item *lip, int shutdown_type);