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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 EFDB8C4360C for ; Fri, 27 Sep 2019 17:16:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDC8A217D9 for ; Fri, 27 Sep 2019 17:16:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727079AbfI0RQc (ORCPT ); Fri, 27 Sep 2019 13:16:32 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:36552 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726251AbfI0RQc (ORCPT ); Fri, 27 Sep 2019 13:16:32 -0400 Received: by mail-pl1-f193.google.com with SMTP id f19so1352045plr.3; Fri, 27 Sep 2019 10:16:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=RNfU8SMnxj+higWP0jV8ynN/lW/e0hOoNDbR3t713zo=; b=lIEKSsgV6WVwYYze9xLZwYxndKC2iV3LjEv+Yfh8wRc9R4/x41jkUz6r1Sl1K1mMbS RR+vG5rFrCFAzgaOWtYvPxRJld9c3C8cj0RNKAe1GeCVWOCX4/Ksaz9DPOGxR2h8T/9r fC4T0uSZlhOMWR7FKiXwZP90dbWe/PdqkQqx3WG0foxUpZrQhJaSumDxfQVGKyjJpYJk UONeNLTAn8bbRmMdKRfBB8wjznXCPd4wsTjjqMabJBXUAUfbdPvrkIdY8LoYOeKugJWm WSQTKaBWZLYsjQNktpsCvp7XkpK7eBTpJi7K9x7j97FsvbqeoA7Lv/Zk8l4L+Weof0Pd piZQ== X-Gm-Message-State: APjAAAW0rvdX4ys8GfyTdIiWWbRqXGcq57hEoUu69vs7QWA5APfgwu1i NdLzuEjQGKDTMm+f6fORLUE= X-Google-Smtp-Source: APXvYqzcL/Tqhb5gG2ywYAm1G7rYdRw8swzeDVXQKsFWKzH09mnNAcXt+jlZgTP9aiz8MZHqn+AKJw== X-Received: by 2002:a17:902:d681:: with SMTP id v1mr5972574ply.310.1569604591178; Fri, 27 Sep 2019 10:16:31 -0700 (PDT) Received: from desktop-bart.svl.corp.google.com ([2620:15c:2cd:202:4308:52a3:24b6:2c60]) by smtp.gmail.com with ESMTPSA id i1sm4345760pfg.2.2019.09.27.10.16.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Sep 2019 10:16:30 -0700 (PDT) Subject: Re: [PATCH v4 17/25] ibnbd: client: main functionality To: Roman Penyaev Cc: Danil Kipnis , Jack Wang , linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, Jens Axboe , Christoph Hellwig , Sagi Grimberg , Jason Gunthorpe , Doug Ledford , rpenyaev@suse.de, Jack Wang References: <20190620150337.7847-1-jinpuwang@gmail.com> <20190620150337.7847-18-jinpuwang@gmail.com> <5c5ff7df-2cce-ec26-7893-55911e4d8595@acm.org> <6f677d56-82b3-a321-f338-cbf8ff4e83eb@acm.org> From: Bart Van Assche Message-ID: <84f5e08b-9586-8e6d-3e35-ce6f1976ba31@acm.org> Date: Fri, 27 Sep 2019 10:16:28 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 9/27/19 9:50 AM, Roman Penyaev wrote: > On Fri, Sep 27, 2019 at 6:37 PM Bart Van Assche wrote: >> I agree that BLK_MQ_F_HOST_TAGS partitions a tag set across hardware >> queues while ibnbd shares a single tag set across multiple hardware >> queues. Since such sharing may be useful for other block drivers, isn't >> that something that should be implemented in the block layer core >> instead of in the ibnbd driver? If that logic would be moved into the >> block layer core, would that allow to reuse the queue restarting logic >> that already exists in the block layer core? > > Definitely yes, but what other block drivers you have in mind? I'd like to hear the opinion of Jens and Christoph about this topic. My concern is that if the code for sharing a tag set across hwqs stays in the ibnbd driver and if another block driver is submitted in the future that needs the same logic that in order to end up with a single implementation of the tag set sharing code that the authors of the new driver would have to be asked to modify the ibnbd driver. I think it would be inappropriate to ask the authors of such a new driver to modify the ibnbd driver. Bart.