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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 1BD76C4332B for ; Tue, 24 Mar 2020 09:47:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E3D602051A for ; Tue, 24 Mar 2020 09:47:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727138AbgCXJrU (ORCPT ); Tue, 24 Mar 2020 05:47:20 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:51826 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726129AbgCXJrT (ORCPT ); Tue, 24 Mar 2020 05:47:19 -0400 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 534E12E87DCB9A5B1249; Tue, 24 Mar 2020 17:47:10 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.204) with Microsoft SMTP Server (TLS) id 14.3.487.0; Tue, 24 Mar 2020 17:47:04 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: fix long latency due to discard during umount From: Chao Yu To: Sahitya Tummala , Jaegeuk Kim , CC: References: <1584506689-5041-1-git-send-email-stummala@codeaurora.org> <54ae330b-ac9b-7968-fa0a-95db6737e3ea@huawei.com> Message-ID: <7804a289-ee55-930c-8b6a-52697d3db679@huawei.com> Date: Tue, 24 Mar 2020 17:47:03 +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: <54ae330b-ac9b-7968-fa0a-95db6737e3ea@huawei.com> 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 On 2020/3/24 17:08, Chao Yu wrote: > On 2020/3/18 12:44, Sahitya Tummala wrote: >> F2FS already has a default timeout of 5 secs for discards that >> can be issued during umount, but it can take more than the 5 sec >> timeout if the underlying UFS device queue is already full and there >> are no more available free tags to be used. In that case, submit_bio() >> will wait for the already queued discard requests to complete to get >> a free tag, which can potentially take way more than 5 sec. >> >> Fix this by submitting the discard requests with REQ_NOWAIT >> flags during umount. This will return -EAGAIN for UFS queue/tag full >> scenario without waiting in the context of submit_bio(). The FS can >> then handle these requests by retrying again within the stipulated >> discard timeout period to avoid long latencies. BTW, I guess later we can add nowait logic as a sub policy of discard_policy, then DPOLICY_BG would be more configurable with this nowait policy support. Thanks, >> >> Signed-off-by: Sahitya Tummala > > Reviewed-by: Chao Yu > > Thanks, > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > . >