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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BB67AC25B7D for ; Wed, 22 May 2024 13:12:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jQOQAWJQIzcAHCNFbYDIo9HGTOvHOu6U/O7t/i3sg5Q=; b=Hq5XFZNnRwQlGVvrCSoNs8T2l8 L42lhelYxABLdjMutqRykw9pfGYgA0Fekou1Ggl2DQwe5z6jhin1BJ4IWo29fJXgx+CI5H19DJgru cujnIzw/nrTpgw0M/IoUX7DGGNyzsX3H2BPitpc1ijQJfHenQ87U49E/Rw1v50k64ZHw48Z36o4mL I3WcJd+rbW2tuqV4+BhQTsmmLynazr0YeheHivR09QBJStxUbtFoav3D4BmdgiQGP20ujyJ5ZZVvG EamFR8ydq4Tf3MqapgpNmXwn4asy0roSdR4Q9r4ltim4IyzZqB3kMwSkcF9jb6FTfJ4ndjxe1ioeV WSkWOHgw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s9llr-000000031H7-0w0g; Wed, 22 May 2024 13:12:43 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s9llm-000000031Gb-06bv for linux-nvme@lists.infradead.org; Wed, 22 May 2024 13:12:39 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1716383554; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jQOQAWJQIzcAHCNFbYDIo9HGTOvHOu6U/O7t/i3sg5Q=; b=aLIFVmS2ZTvzpcWi9LqW1RWNTdMYVqUVbRHvJ4zQTGgGZQxRLIzla30pmuOYWP9ehJN1LK mvI+8w1UgI11GoPDIXaSjKyUK00fDt3dVZtFHa22tcLbQLB9iz6hZGQYx1njzAJ3+MCpBz O1JuWjbsyosIGzBrMeljSCGuTvP22Bo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-655-Oa7STFArNvCcSFCjpvsoaQ-1; Wed, 22 May 2024 09:12:31 -0400 X-MC-Unique: Oa7STFArNvCcSFCjpvsoaQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B3D94800CA5; Wed, 22 May 2024 13:12:30 +0000 (UTC) Received: from [10.22.8.193] (unknown [10.22.8.193]) by smtp.corp.redhat.com (Postfix) with ESMTP id ED17A2026D68; Wed, 22 May 2024 13:12:29 +0000 (UTC) Message-ID: Date: Wed, 22 May 2024 09:12:29 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] nvme: multipath: Implemented new iopolicy "queue-depth" To: Nilay Shroff , Sagi Grimberg , kbusch@kernel.org, hch@lst.de, emilne@redhat.com Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, jrani@purestorage.com, randyj@purestorage.com, hare@kernel.org References: <20240520202045.427110-1-jmeneghi@redhat.com> <20240520202045.427110-2-jmeneghi@redhat.com> <945416af-3f8b-40b5-9681-49973beb2cb2@linux.ibm.com> <3b8d33db-f2c3-469a-bfa0-8fc52594f243@grimberg.me> <95fe3168-ec39-4932-b9fc-26484de49191@linux.ibm.com> <073ae18a-a80e-4a95-a093-36210a3bb230@grimberg.me> <8f5ad047-be0b-471c-a708-f2bc464d29ef@redhat.com> Content-Language: en-US From: John Meneghini Organization: RHEL Core Storge Team In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240522_061238_161380_77B3FA68 X-CRM114-Status: GOOD ( 14.12 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 5/22/24 06:48, Nilay Shroff wrote: >> I has received quite a bit of testing with failover and controller resets.  I shared some of the testing that was done at LSFMM last week. >> >> It has received enough testing to make me confident that this code is safe.  That is: it won't panic, corrupt data, or otherwise do any harm.  We believe the error paths will not be affected by this change... but I agree that running the error paths could negatively impact the accuracy of the nr_active counters... which could lead to an inaccurate outcome with the queue-depth policy. >> >> I agree the nr_counter initialize should move to nvme_mpath_init_identify(), or maybe be done there in addition to in nvme_mpath_init_ctrl(). I'm will to make that change now... if that's what people want.  I don't think it would require any extensive retesting. >> >> /John >> >> > I think with Keith's recent proposed patch for fixing io accounting on failover, the > nvme_mpath_end_request() would be called even for cancelled IO and so the nr_active > counter shall be adjusted correctly for cancelled IO requests. Having said that, IMO > you shall consider moving initialization of nr_active counter to nvme_mpath_init_identify() > as that's common function invoked from regular controller initialization code path as well > the reset code path. Agreed. I'll do that in V4 of the patch set. /John