From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 097BC13D29F for ; Tue, 21 May 2024 14:44:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716302656; cv=none; b=FAUTAJAaruP4OfE+LW1uijWFmI95Ay3qCq7Howt5imgX6PJc/ALX1nnbTQYRwl3sS9HHel1dBCg6lucMXSTKGFpN5xRS4RzI9cOII7cIqinFpongb3LpKsHzx9EyfpXmjA58Jl6zwt8sOLEJYSYNnHYNvLj7PUlkwuzrM9rlyQg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716302656; c=relaxed/simple; bh=IbiMENtJRUpAYj9BkGqABsQrjw2WB0RIdq7to/XUFO8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=n8bCkEQfhz4hOyzqBy+f2v4ZDbA9Y3zLUToXQtQ1cL4O2nvue42OtojJ6IFNQfI+y+Pcxa6SE013veI3UN5h0tZWCBWtIi5bj9O9HgdIK8Eno+dXFNYA+Mm4ZrV6SufvpZ92pR41cBRn4aU4OLRbZNDNXMxYkOlVm7gEmFbFtfY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=UanXuMl4; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UanXuMl4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1716302654; 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=UanXuMl4J510wb/5rpQh0O1mZ4aIBHL1KkUX3YBd4bAZhPxfuyGrLXi+DVM+xFGQldaaHK 0tVUuyeqge8+uwIoFXqSB+FGBDtIErMPM7XWKVtcjXG6UmoWWfpfB6kSkmj8g1BUjDZ3Fp 4qfuNimYavhoJw1V9P+QIh3QlQKYu98= 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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