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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 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 B3FD0C49ED7 for ; Mon, 16 Sep 2019 16:43:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CE1921852 for ; Mon, 16 Sep 2019 16:43:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="M5A/5P5b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390098AbfIPQnC (ORCPT ); Mon, 16 Sep 2019 12:43:02 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:46256 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727981AbfIPQnC (ORCPT ); Mon, 16 Sep 2019 12:43:02 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x8GGEPGu153094; Mon, 16 Sep 2019 16:42:59 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=WRy229U4EhbdkBD9mP4h0IKWqz95ElPrP/6sbAM1T6w=; b=M5A/5P5bBKHJ89EDMd34xBOY2abQwrgEXsyXG5Ti/wxK61xnOgZBQQji2mOonyHqlSF+ k5iEEDeVrEB+GB8xx9No636SCWRc+D+0ylSI9uGVMkw4vp212ERrbb8GwZYZOcUmDaid 7tF3eiRPMUCIQ14Lze6s/ywP5ihbcfktUABEiocLKkDxf7hgkyJ4l0ASkTtyNtaUqZfQ 0xP6SPdS00KX7rWT9I1haHOWDSsIArtj6alvbmqEgUKpSGpT+onyLERGoJS/hWZUQNGe KbhIroTiiaZA5XKyizKHFEyKEUl5YBpjflcJ6W/1aqAjmTBpxag2i/qHhjhm5buEo7ZS MA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 2v0ruqgqxr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 16 Sep 2019 16:42:59 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x8GGDYGj109696; Mon, 16 Sep 2019 16:42:58 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 2v0p8uvbqm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 16 Sep 2019 16:42:58 +0000 Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x8GGgvme026356; Mon, 16 Sep 2019 16:42:57 GMT Received: from localhost (/10.159.225.108) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 16 Sep 2019 09:42:56 -0700 Date: Mon, 16 Sep 2019 09:42:55 -0700 From: "Darrick J. Wong" To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 2/2] xfs: hard limit the background CIL push Message-ID: <20190916164255.GA2229799@magnolia> References: <20190909015159.19662-1-david@fromorbit.com> <20190909015159.19662-3-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190909015159.19662-3-david@fromorbit.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9382 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909160167 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9382 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909160167 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Mon, Sep 09, 2019 at 11:51:59AM +1000, Dave Chinner wrote: > From: Dave Chinner > > In certain situations the background CIL push can be indefinitely > delayed. While we have workarounds from the obvious cases now, it > doesn't solve the underlying issue. This issue is that there is no > upper limit on the CIL where we will either force or wait for > a background push to start, hence allowing the CIL to grow without > bound until it consumes all log space. > > To fix this, add a new wait queue to the CIL which allows background > pushes to wait for the CIL context to be switched out. This happens > when the push starts, so it will allow us to block incoming > transaction commit completion until the push has started. This will > only affect processes that are running modifications, and only when > the CIL threshold has been significantly overrun. > > This has no apparent impact on performance, and doesn't even trigger > until over 45 million inodes had been created in a 16-way fsmark > test on a 2GB log. That was limiting at 64MB of log space used, so > the active CIL size is only about 3% of the total log in that case. > The concurrent removal of those files did not trigger the background > sleep at all. > > Signed-off-by: Dave Chinner > --- > fs/xfs/xfs_log_cil.c | 30 +++++++++++++++++++++++++----- > fs/xfs/xfs_log_priv.h | 1 + > 2 files changed, 26 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c > index ef652abd112c..eec9b32f5e08 100644 > --- a/fs/xfs/xfs_log_cil.c > +++ b/fs/xfs/xfs_log_cil.c > @@ -670,6 +670,11 @@ xlog_cil_push( > push_seq = cil->xc_push_seq; > ASSERT(push_seq <= ctx->sequence); > > + /* > + * Wake up any background push waiters now this context is being pushed. > + */ > + wake_up_all(&ctx->push_wait); > + > /* > * Check if we've anything to push. If there is nothing, then we don't > * move on to a new sequence number and so we have to be able to push > @@ -746,6 +751,7 @@ xlog_cil_push( > */ > INIT_LIST_HEAD(&new_ctx->committing); > INIT_LIST_HEAD(&new_ctx->busy_extents); > + init_waitqueue_head(&new_ctx->push_wait); > new_ctx->sequence = ctx->sequence + 1; > new_ctx->cil = cil; > cil->xc_ctx = new_ctx; > @@ -898,7 +904,7 @@ xlog_cil_push_work( > * checkpoint), but commit latency and memory usage limit this to a smaller > * size. > */ > -static void > +static bool > xlog_cil_push_background( > struct xlog *log) > { > @@ -915,14 +921,28 @@ xlog_cil_push_background( > * space available yet. > */ > if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log)) > - return; > + return false; > > spin_lock(&cil->xc_push_lock); > if (cil->xc_push_seq < cil->xc_current_sequence) { > cil->xc_push_seq = cil->xc_current_sequence; > queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work); > } > + > + /* > + * If we are well over the space limit, throttle the work that is being > + * done until the push work on this context has begun. This will prevent > + * the CIL from violating maximum transaction size limits if the CIL > + * push is delayed for some reason. > + */ > + if (cil->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log) * 2) { > + up_read(&cil->xc_ctx_lock); > + trace_printk("CIL space used %d", cil->xc_ctx->space_used); Needs a real tracepoint before this drops RFC status. > + xlog_wait(&cil->xc_ctx->push_wait, &cil->xc_push_lock); > + return true; > + } > spin_unlock(&cil->xc_push_lock); > + return false; > > } > > @@ -1038,9 +1058,8 @@ xfs_log_commit_cil( > if (lip->li_ops->iop_committing) > lip->li_ops->iop_committing(lip, xc_commit_lsn); > } > - xlog_cil_push_background(log); > - > - up_read(&cil->xc_ctx_lock); > + if (!xlog_cil_push_background(log)) > + up_read(&cil->xc_ctx_lock); Hmmmm... the return value here tell us if ctx_lock has been dropped. /me wonders if this would be cleaner if xlog_cil_push_background returned having called up_read...? --D > } > > /* > @@ -1199,6 +1218,7 @@ xlog_cil_init( > > INIT_LIST_HEAD(&ctx->committing); > INIT_LIST_HEAD(&ctx->busy_extents); > + init_waitqueue_head(&ctx->push_wait); > ctx->sequence = 1; > ctx->cil = cil; > cil->xc_ctx = ctx; > diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h > index 187a43ffeaf7..466259fd1e4a 100644 > --- a/fs/xfs/xfs_log_priv.h > +++ b/fs/xfs/xfs_log_priv.h > @@ -247,6 +247,7 @@ struct xfs_cil_ctx { > struct xfs_log_vec *lv_chain; /* logvecs being pushed */ > struct list_head iclog_entry; > struct list_head committing; /* ctx committing list */ > + wait_queue_head_t push_wait; /* background push throttle */ > struct work_struct discard_endio_work; > }; > > -- > 2.23.0.rc1 >