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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 86981C43331 for ; Mon, 30 Mar 2020 08:38:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 606932073B for ; Mon, 30 Mar 2020 08:38:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729701AbgC3IiV (ORCPT ); Mon, 30 Mar 2020 04:38:21 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:44048 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726017AbgC3IiU (ORCPT ); Mon, 30 Mar 2020 04:38:20 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 98C441D36927062BC959; Mon, 30 Mar 2020 16:38:15 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.201) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 30 Mar 2020 16:38:11 +0800 Subject: Re: [PATCH] f2fs: fix long latency due to discard during umount To: Sahitya Tummala CC: Jaegeuk Kim , , 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> From: Chao Yu Message-ID: <9adc5c7e-7936-bac7-58b1-50631f8ac5eb@huawei.com> Date: Mon, 30 Mar 2020 16:38:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200330065335.GT20234@codeaurora.org> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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. >