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 CDAEFC25B74 for ; Tue, 21 May 2024 14:44:21 +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=WZE79ngHiPYMsknTkJKUUOGKy5jq6C5Ns0sjPmwNKqk=; b=zqSbsQzcRC60dP3Ko6u2d9PWKH dFq7Kkay/kQfaP1q9OY8kt1vFCOrrxDkexwgoOlUv6hcZ82d59hC8pBloJnooZNgSDFihE1iJ1MjZ locXZVSAZHShbqWaHeW5ylDD6lGVwADRe82rY+S+5kbgjllOwzrVz92AjQd9dYHT69zjxM1PXCKLA PPi6oI8fYmdNi8fYN3TAh93AKhBkaaoZxinFZvY2uk8H4007ZVVXjqE7S7meboBVZIAnqxO+yZ0sL DP5F10Tkbu/fhO6maUuRJ6vGYZNpMoWtH/qfhGlZ3b3gnSVP5+B5tDt5Fcts4Lj+jHbBjdaKxRAO1 sHK9YKFw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s9Qiv-00000000DSU-21TE; Tue, 21 May 2024 14:44:17 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s9Qis-00000000DRV-18xL for linux-nvme@lists.infradead.org; Tue, 21 May 2024 14:44:15 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1716302653; 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=WZE79ngHiPYMsknTkJKUUOGKy5jq6C5Ns0sjPmwNKqk=; b=ZD51Cer6X/hmwtWqV4eTwRFJb59s8MlbZPQ0CHHMQK4J9k5+77sCh521/YST2nOTAOHZ4J 0BbQ7V8VmJ4sEgPDBBuTlslrTpW3F1hP1nDpdyoEBawFJEzah+NGpMicMVNf9eyvQ9HNP1 Cz6IBlvoN30PLCUiqYp3ffhPCvsYOkg= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-74-eIJdvIDPPYGPxIVEjg4jmQ-1; Tue, 21 May 2024 10:44:10 -0400 X-MC-Unique: eIJdvIDPPYGPxIVEjg4jmQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (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 45D4B3C0C2C4; Tue, 21 May 2024 14:44:09 +0000 (UTC) Received: from [10.22.8.193] (unknown [10.22.8.193]) by smtp.corp.redhat.com (Postfix) with ESMTP id 409B31C008BB; Tue, 21 May 2024 14:44:08 +0000 (UTC) Message-ID: <8f5ad047-be0b-471c-a708-f2bc464d29ef@redhat.com> Date: Tue, 21 May 2024 10:44:07 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] nvme: multipath: Implemented new iopolicy "queue-depth" To: Sagi Grimberg , Nilay Shroff , 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> 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 10.11.54.7 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240521_074414_648187_D18A1503 X-CRM114-Status: GOOD ( 13.23 ) 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 5/21/24 06:16, Sagi Grimberg wrote: >>> >>> Exactly, nvme_mpath_init_ctrl resets the counter. >> >> Except you're right, the counter reset needs to move to nvme_mpath_init_identify() >> or some place that is called on every controller reset. > > This however raises the question of how much failover/reset tests this patch has seen... 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