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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 73B37ECE598 for ; Wed, 9 Oct 2019 03:22:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 30ABC2133F for ; Wed, 9 Oct 2019 03:22:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 30ABC2133F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=fromorbit.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7D15C8E0018; Tue, 8 Oct 2019 23:21:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3099A8E0019; Tue, 8 Oct 2019 23:21:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 12EFC8E0016; Tue, 8 Oct 2019 23:21:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0171.hostedemail.com [216.40.44.171]) by kanga.kvack.org (Postfix) with ESMTP id A50CA8E000D for ; Tue, 8 Oct 2019 23:21:34 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 418B14408 for ; Wed, 9 Oct 2019 03:21:34 +0000 (UTC) X-FDA: 76022796108.28.drop83_2ab60e20f1005 X-HE-Tag: drop83_2ab60e20f1005 X-Filterd-Recvd-Size: 7961 Received: from mail105.syd.optusnet.com.au (mail105.syd.optusnet.com.au [211.29.132.249]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Oct 2019 03:21:33 +0000 (UTC) Received: from dread.disaster.area (pa49-181-226-196.pa.nsw.optusnet.com.au [49.181.226.196]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id 79E96362EB8; Wed, 9 Oct 2019 14:21:27 +1100 (AEDT) Received: from discord.disaster.area ([192.168.253.110]) by dread.disaster.area with esmtp (Exim 4.92.2) (envelope-from ) id 1iI2XW-0006BK-RT; Wed, 09 Oct 2019 14:21:26 +1100 Received: from dave by discord.disaster.area with local (Exim 4.92) (envelope-from ) id 1iI2XW-00039E-PS; Wed, 09 Oct 2019 14:21:26 +1100 From: Dave Chinner To: linux-xfs@vger.kernel.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: [PATCH 07/26] xfs: tail updates only need to occur when LSN changes Date: Wed, 9 Oct 2019 14:21:05 +1100 Message-Id: <20191009032124.10541-8-david@fromorbit.com> X-Mailer: git-send-email 2.23.0.rc1 In-Reply-To: <20191009032124.10541-1-david@fromorbit.com> References: <20191009032124.10541-1-david@fromorbit.com> MIME-Version: 1.0 X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.2 cv=D+Q3ErZj c=1 sm=1 tr=0 a=dRuLqZ1tmBNts2YiI0zFQg==:117 a=dRuLqZ1tmBNts2YiI0zFQg==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=XobE76Q3jBoA:10 a=20KFwNOVAAAA:8 a=W3SVq3cs_kfo-QxLsoMA:9 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 --- 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..0d5eee456b0c 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 =3D false; + xfs_lsn_t tail_lsn =3D 0; =20 /* 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 =3D=3D INODE_ITEM(blip)->ili_flush_lsn) - mlip_changed |=3D xfs_ail_delete_one(ailp, blip); - else { + blip->li_lsn =3D=3D 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 =3D xfs_ail_delete_one(ailp, blip); + if (!tail_lsn && lsn) + tail_lsn =3D lsn; + } else { xfs_clear_li_failed(blip); } } - xfs_ail_update_finish(ailp, mlip_changed); + xfs_ail_update_finish(ailp, tail_lsn); } =20 /* 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 th= e last * item in the AIL. */ +static xfs_lsn_t +__xfs_ail_min_lsn( + struct xfs_ail *ailp) +{ + struct xfs_log_item *lip =3D 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 =3D 0; - struct xfs_log_item *lip; + xfs_lsn_t lsn; =20 spin_lock(&ailp->ail_lock); - lip =3D xfs_ail_min(ailp); - if (lip) - lsn =3D lip->li_lsn; + lsn =3D __xfs_ail_min_lsn(ailp); spin_unlock(&ailp->ail_lock); =20 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 =3D ailp->ail_mount; =20 - if (!do_tail_update) { + /* if the tail lsn hasn't changed, don't do updates or wakeups. */ + if (!old_lsn || old_lsn =3D=3D __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 =3D 0; + xfs_lsn_t tail_lsn =3D 0; int i; LIST_HEAD(tmp); =20 @@ -745,9 +754,10 @@ xfs_trans_ail_update_bulk( continue; =20 trace_xfs_ail_move(lip, lip->li_lsn, lsn); + if (mlip =3D=3D lip && !tail_lsn) + tail_lsn =3D lip->li_lsn; + xfs_ail_delete(ailp, lip); - if (mlip =3D=3D lip) - mlip_changed =3D 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); =20 - xfs_ail_update_finish(ailp, mlip_changed); + xfs_ail_update_finish(ailp, tail_lsn); } =20 -bool +/* + * Delete one log item from the AIL. + * + * If this item was at the tail of the AIL, return the LSN of the log it= em so + * that we can use it to check if the LSN of the tail of the log has mov= ed + * 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 =3D xfs_ail_min(ailp); + xfs_lsn_t lsn =3D lip->li_lsn; =20 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 =3D 0; =20 - return mlip =3D=3D lip; + if (mlip =3D=3D lip) + return lsn; + return 0; } =20 /** @@ -805,7 +825,7 @@ xfs_trans_ail_delete( int shutdown_type) { struct xfs_mount *mp =3D ailp->ail_mount; - bool need_update; + xfs_lsn_t tail_lsn; =20 if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) { spin_unlock(&ailp->ail_lock); @@ -818,8 +838,8 @@ xfs_trans_ail_delete( return; } =20 - need_update =3D xfs_ail_delete_one(ailp, lip); - xfs_ail_update_finish(ailp, need_update); + tail_lsn =3D xfs_ail_delete_one(ailp, lip); + xfs_ail_update_finish(ailp, tail_lsn); } =20 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); } =20 -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); --=20 2.23.0.rc1