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[209.132.180.67]) by mx.google.com with ESMTP id l4si6806285otf.195.2020.03.30.20.12.23; Mon, 30 Mar 2020 20:12:36 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@mg.codeaurora.org header.s=smtp header.b="ZZ93h/G1"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729372AbgCaDK5 (ORCPT + 99 others); Mon, 30 Mar 2020 23:10:57 -0400 Received: from mail27.static.mailgun.info ([104.130.122.27]:48649 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727464AbgCaDK4 (ORCPT ); Mon, 30 Mar 2020 23:10:56 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1585624255; h=In-Reply-To: Content-Type: MIME-Version: References: Message-ID: Subject: Cc: To: From: Date: Sender; bh=bcm3LyrGOQHUR76njTvQpJ4pk9O8c7rYDVbC8J3qwtk=; b=ZZ93h/G1iO2IiZ2b6KGhFr1wL5mIqOHSwQKkbjaGroYUYZY6vyXqRYpn2EEa3Y1lwNqbkdke vrotqoMVxQqevF3r0vyRy5Lfl8c2uaD+gpMSQR3H/fwy2RmkdJZJWNRpdZv3WTuU+pSjJ5BW WM3X6YtlhMtEPhQhU8uV38QW7AQ= X-Mailgun-Sending-Ip: 104.130.122.27 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e82b4ab.7f841e625fb8-smtp-out-n05; Tue, 31 Mar 2020 03:10:35 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 378D5C43637; Tue, 31 Mar 2020 03:10:34 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-caf-mail-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=2.0 tests=ALL_TRUSTED,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.0 Received: from codeaurora.org (blr-c-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: stummala) by smtp.codeaurora.org (Postfix) with ESMTPSA id E6722C433F2; Tue, 31 Mar 2020 03:10:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org E6722C433F2 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=stummala@codeaurora.org Date: Tue, 31 Mar 2020 08:40:27 +0530 From: Sahitya Tummala To: Chao Yu Cc: Jaegeuk Kim , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, stummala@codeaurora.org Subject: Re: [f2fs-dev] [PATCH] f2fs: fix long latency due to discard during umount Message-ID: <20200331031027.GY20234@codeaurora.org> References: <1584506689-5041-1-git-send-email-stummala@codeaurora.org> <29d4adc4-482d-3d92-1470-3405989ea231@huawei.com> <20200326133700.GR20234@codeaurora.org> <2b0d8d4c-a981-4edc-d8ca-fe199a63ea79@huawei.com> <20200327030542.GS20234@codeaurora.org> <20200330065335.GT20234@codeaurora.org> <9adc5c7e-7936-bac7-58b1-50631f8ac5eb@huawei.com> <5ec3b2e1-162c-e62d-1834-100c8ae39ff7@huawei.com> <20200330105122.GV20234@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sure Chao. Let us put this patch on hold for now then. Jaeguek, Please drop this patch from your tree for time being as it needs further discussion. Thanks, On Tue, Mar 31, 2020 at 09:46:30AM +0800, Chao Yu wrote: > Hi Sahitya, > > On 2020/3/30 18:51, Sahitya Tummala wrote: > > Hi Chao, > > > > On Mon, Mar 30, 2020 at 06:16:40PM +0800, Chao Yu wrote: > >> On 2020/3/30 16:38, Chao Yu wrote: > >>> Hi Sahitya, > >>> > >>> Bad news, :( I guess we didn't catch the root cause, as after applying v3, > >>> I still can reproduce this issue: > >>> > >>> generic/003 10s ... 30s > >> > >> I use zram as backend device of fstest, > >> > >> Call Trace: > >> dump_stack+0x66/0x8b > >> f2fs_submit_discard_endio+0x88/0xa0 [f2fs] > >> generic_make_request_checks+0x70/0x5f0 > >> generic_make_request+0x3e/0x2e0 > >> submit_bio+0x72/0x140 > >> __submit_discard_cmd.isra.50+0x4a8/0x710 [f2fs] > >> __issue_discard_cmd+0x171/0x3a0 [f2fs] > >> > >> Does this mean zram uses single queue, so we may always fail to submit 'nowait' > >> IO due to below condition: > >> > >> /* > >> * Non-mq queues do not honor REQ_NOWAIT, so complete a bio > >> * with BLK_STS_AGAIN status in order to catch -EAGAIN and > >> * to give a chance to the caller to repeat request gracefully. > >> */ > >> if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q)) { > >> status = BLK_STS_AGAIN; > >> goto end_io; > >> } > >> > > > > Yes, I have also just figured out that as the reason. But most of the real block > > devic drivers support MQ. Can we thus fix this case by checking for MQ status > > before enabling REQ_NOWAIT as below? Please share your comments. > > > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > index cda7935..e7e2ffe 100644 > > --- a/fs/f2fs/segment.c > > +++ b/fs/f2fs/segment.c > > @@ -1131,7 +1131,9 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi, > > > > flag = dpolicy->sync ? REQ_SYNC : 0; > > - flag |= dpolicy->type == DPOLICY_UMOUNT ? REQ_NOWAIT : 0; > > + > > + if (sbi->sb->s_bdev->bd_queue && queue_is_mq(sbi->sb->s_bdev->bd_queue)) > > + flag |= dpolicy->type == DPOLICY_UMOUNT ? REQ_NOWAIT : 0; > > IMO, it's too tight to couple with block layer logic? however, I don't have > any better idea about the solution. > > Anyway, I guess we can Cc to Jan and block mailing list for comments to see > whether there is a better solution. > > Thoughts? > > Thanks, > > > > > if (dc->state != D_PREP) > > return 0; > > > > Thanks, > > > >> > >> > >>> > >>> Thanks, > >>> > >>> On 2020/3/30 14:53, Sahitya Tummala wrote: > >>>> Hi Chao, > >>>> > >>>> On Fri, Mar 27, 2020 at 08:35:42AM +0530, Sahitya Tummala wrote: > >>>>> On Fri, Mar 27, 2020 at 09:51:43AM +0800, Chao Yu wrote: > >>>>>> > >>>>>> With this patch, most of xfstest cases cost 5 * n second longer than before. > >>>>>> > >>>>>> E.g. generic/003, during umount(), we looped into retrying one bio > >>>>>> submission. > >>>>>> > >>>>>> [61279.829724] F2FS-fs (zram1): Found nat_bits in checkpoint > >>>>>> [61279.885337] F2FS-fs (zram1): Mounted with checkpoint version = 5cf3cb8e > >>>>>> [61281.912832] submit discard bio start [23555,1] > >>>>>> [61281.912835] f2fs_submit_discard_endio [23555,1] err:-11 > >>>>>> [61281.912836] submit discard bio end [23555,1] > >>>>>> [61281.912836] move dc to retry list [23555,1] > >>>>>> > >>>>>> ... > >>>>>> > >>>>>> [61286.881212] submit discard bio start [23555,1] > >>>>>> [61286.881217] f2fs_submit_discard_endio [23555,1] err:-11 > >>>>>> [61286.881223] submit discard bio end [23555,1] > >>>>>> [61286.881224] move dc to retry list [23555,1] > >>>>>> [61286.905198] submit discard bio start [23555,1] > >>>>>> [61286.905203] f2fs_submit_discard_endio [23555,1] err:-11 > >>>>>> [61286.905205] submit discard bio end [23555,1] > >>>>>> [61286.905206] move dc to retry list [23555,1] > >>>>>> [61286.929157] F2FS-fs (zram1): Issue discard(23555, 23555, 1) failed, ret: -11 > >>>>>> > >>>>>> Could you take a look at this issue? > >>>>> > >>>>> Let me check and get back on this. > >>>> > >>>> I found the issue. The dc with multiple bios is getting requeued again and > >>>> again in case if one of its bio gets -EAGAIN error. Even the successfully > >>>> completed bios are getting requeued again resulting into long latency. > >>>> I have fixed it by splitting the dc in such case so that we can requeue only > >>>> the leftover bios into a new dc and retry that later within the 5 sec timeout. > >>>> > >>>> Please help to review v3 posted and if it looks good, I would like to request > >>>> you to test the earlier regression scenario with it to check the result again? > >>>> > >>>> thanks, > >>>> > >>>>> > >>>>> Thanks, > >>>>> > >>>>>> > >>>>>> Thanks, > >>>>>> > >>>>>>> > >>>>>>> Thanks, > >>>>>>> > >>>>>>>> Thanks, > >>>>>>>> > >>>>>>>>> + break; > >>>>>>>>> + } > >>>>>>>>> + } > >>>>>>>>> > >>>>>>>>> atomic_inc(&dcc->issued_discard); > >>>>>>>>> > >>>>>>>>> @@ -1463,6 +1477,40 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi, > >>>>>>>>> return issued; > >>>>>>>>> } > >>>>>>>>> > >>>>>>>>> +static bool __should_discard_retry(struct f2fs_sb_info *sbi, > >>>>>>> s> > + struct discard_policy *dpolicy) > >>>>>>>>> +{ > >>>>>>>>> + struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info; > >>>>>>>>> + struct discard_cmd *dc, *tmp; > >>>>>>>>> + bool retry = false; > >>>>>>>>> + unsigned long flags; > >>>>>>>>> + > >>>>>>>>> + if (dpolicy->type != DPOLICY_UMOUNT) > >>>>>>>>> + f2fs_bug_on(sbi, 1); > >>>>>>>>> + > >>>>>>>>> + mutex_lock(&dcc->cmd_lock); > >>>>>>>>> + list_for_each_entry_safe(dc, tmp, &(dcc->retry_list), list) { > >>>>>>>>> + if (dpolicy->timeout != 0 && > >>>>>>>>> + f2fs_time_over(sbi, dpolicy->timeout)) { > >>>>>>>>> + retry = false; > >>>>>>>>> + break; > >>>>>>>>> + } > >>>>>>>>> + > >>>>>>>>> + spin_lock_irqsave(&dc->lock, flags); > >>>>>>>>> + if (!dc->bio_ref) { > >>>>>>>>> + dc->state = D_PREP; > >>>>>>>>> + dc->error = 0; > >>>>>>>>> + reinit_completion(&dc->wait); > >>>>>>>>> + __relocate_discard_cmd(dcc, dc); > >>>>>>>>> + retry = true; > >>>>>>>>> + } > >>>>>>>>> + spin_unlock_irqrestore(&dc->lock, flags); > >>>>>>>>> + } > >>>>>>>>> + mutex_unlock(&dcc->cmd_lock); > >>>>>>>>> + > >>>>>>>>> + return retry; > >>>>>>>>> +} > >>>>>>>>> + > >>>>>>>>> static int __issue_discard_cmd(struct f2fs_sb_info *sbi, > >>>>>>>>> struct discard_policy *dpolicy) > >>>>>>>>> { > >>>>>>>>> @@ -1470,12 +1518,13 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi, > >>>>>>>>> struct list_head *pend_list; > >>>>>>>>> struct discard_cmd *dc, *tmp; > >>>>>>>>> struct blk_plug plug; > >>>>>>>>> - int i, issued = 0; > >>>>>>>>> + int i, err, issued = 0; > >>>>>>>>> bool io_interrupted = false; > >>>>>>>>> > >>>>>>>>> if (dpolicy->timeout != 0) > >>>>>>>>> f2fs_update_time(sbi, dpolicy->timeout); > >>>>>>>>> > >>>>>>>>> +retry: > >>>>>>>>> for (i = MAX_PLIST_NUM - 1; i >= 0; i--) { > >>>>>>>>> if (dpolicy->timeout != 0 && > >>>>>>>>> f2fs_time_over(sbi, dpolicy->timeout)) > >>>>>>>>> @@ -1509,7 +1558,10 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi, > >>>>>>>>> break; > >>>>>>>>> } > >>>>>>>>> > >>>>>>>>> - __submit_discard_cmd(sbi, dpolicy, dc, &issued); > >>>>>>>>> + err = __submit_discard_cmd(sbi, dpolicy, dc, &issued); > >>>>>>>>> + if (err == -EAGAIN) > >>>>>>>>> + congestion_wait(BLK_RW_ASYNC, > >>>>>>>>> + DEFAULT_IO_TIMEOUT); > >>>>>>>>> > >>>>>>>>> if (issued >= dpolicy->max_requests) > >>>>>>>>> break; > >>>>>>>>> @@ -1522,6 +1574,10 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi, > >>>>>>>>> break; > >>>>>>>>> } > >>>>>>>>> > >>>>>>>>> + if (!list_empty(&dcc->retry_list) && > >>>>>>>>> + __should_discard_retry(sbi, dpolicy)) > >>>>>>>>> + goto retry; > >>>>>>>>> + > >>>>>>>>> if (!issued && io_interrupted) > >>>>>>>>> issued = -1; > >>>>>>>>> > >>>>>>>>> @@ -1613,6 +1669,12 @@ static unsigned int __wait_discard_cmd_range(struct f2fs_sb_info *sbi, > >>>>>>>>> goto next; > >>>>>>>>> } > >>>>>>>>> > >>>>>>>>> + if (dpolicy->type == DPOLICY_UMOUNT && > >>>>>>>>> + !list_empty(&dcc->retry_list)) { > >>>>>>>>> + wait_list = &dcc->retry_list; > >>>>>>>>> + goto next; > >>>>>>>>> + } > >>>>>>>>> + > >>>>>>>>> return trimmed; > >>>>>>>>> } > >>>>>>>>> > >>>>>>>>> @@ -2051,6 +2113,7 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi) > >>>>>>>>> for (i = 0; i < MAX_PLIST_NUM; i++) > >>>>>>>>> INIT_LIST_HEAD(&dcc->pend_list[i]); > >>>>>>>>> INIT_LIST_HEAD(&dcc->wait_list); > >>>>>>>>> + INIT_LIST_HEAD(&dcc->retry_list); > >>>>>>>>> INIT_LIST_HEAD(&dcc->fstrim_list); > >>>>>>>>> mutex_init(&dcc->cmd_lock); > >>>>>>>>> atomic_set(&dcc->issued_discard, 0); > >>>>>>>>> > >>>>>>> > >>>>> > >>>>> -- > >>>>> -- > >>>>> Sent by a consultant of the Qualcomm Innovation Center, Inc. > >>>>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. > >>>> > >>> > >>> > >>> _______________________________________________ > >>> Linux-f2fs-devel mailing list > >>> Linux-f2fs-devel@lists.sourceforge.net > >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > >>> . > >>> > > -- -- Sent by a consultant of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.