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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 362F9C433EF for ; Tue, 29 Mar 2022 12:41:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236495AbiC2MnX (ORCPT ); Tue, 29 Mar 2022 08:43:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236459AbiC2Mmr (ORCPT ); Tue, 29 Mar 2022 08:42:47 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 03D21211EC7; Tue, 29 Mar 2022 05:40:48 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KSTdm4c2WzfZKw; Tue, 29 Mar 2022 20:39:08 +0800 (CST) Received: from dggpemm500017.china.huawei.com (7.185.36.178) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 29 Mar 2022 20:40:46 +0800 Received: from [10.174.178.220] (10.174.178.220) by dggpemm500017.china.huawei.com (7.185.36.178) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 29 Mar 2022 20:40:45 +0800 Subject: Re: [REQUEST DISCUSS]: speed up SCSI error handle for host with massive devices To: Steffen Maier , , "linux-kernel@vger.kernel.org" , "James E.J. Bottomley" , "Martin K. Petersen" , Mike Christie , Lee Duncan CC: Wu Bo , Feilong Lin , References: <71e09bb4-ff0a-23fe-38b4-fe6425670efa@huawei.com> From: Wenchao Hao Message-ID: <331aafe1-df9b-cae4-c958-9cf1800e389a@huawei.com> Date: Tue, 29 Mar 2022 20:40:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.220] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500017.china.huawei.com (7.185.36.178) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/3/29 18:56, Steffen Maier wrote: > On 3/29/22 11:06, Wenchao Hao wrote: >> SCSI timeout would call scsi_eh_scmd_add() on some conditions, host would be set >> to SHOST_RECOVERY state. Once host enter SHOST_RECOVERY, IOs submitted to all >> devices in this host would not succeed until the scsi_error_handler() finished. >> The scsi_error_handler() might takes long time to be done, it's unbearable when >> host has massive devices. >> >> I want to ask is anyone applying another error handler flow to address this >> phenomenon? >> >> I think we can move some operations(like scsi get sense, scsi send startunit >> and scsi device reset) out of scsi_unjam_host(), to perform these operations >> without setting host to SHOST_RECOVERY? It would reduce the time of block the >> whole host. >> >> Waiting for your discussion. > > We already have "async" aborts before even entering scsi_eh. So your use case seems to imply that those aborts fail and we enter scsi_eh? > Yes, I mean when scsi_abort_command() failed and scsi_eh_scmd_add() is called. > There's eh_deadline for limiting the time spent in escalation of scsi_eh, and instead directly go to host reset. Would this help? > > The deadline seems not helpful. What we want to see is a single LUN's command error would not stop other LUNs which share the same host. So my plan is to move reset LUN out from scsi_unjam_host() which run with host set to SHOST_RECOVERY.