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=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E4F66C433EF for ; Tue, 7 Sep 2021 23:04:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C192461139 for ; Tue, 7 Sep 2021 23:04:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344087AbhIGXFn (ORCPT ); Tue, 7 Sep 2021 19:05:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:48822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240690AbhIGXFk (ORCPT ); Tue, 7 Sep 2021 19:05:40 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 365DD61102; Tue, 7 Sep 2021 23:04:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631055873; bh=U4r90XGeMFMBTYQzJqJqJ72n/aEzus0q4Z98AOX2grc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sKXNN3dc3jccHx69/sKD47gbQLIRPr5FvdMGBsnJ/eUfbMNTLqUqNfWSvns+I69ck U25GKT7tGRJbAWVj0zvnCcxOB6w4HzBT1Fe6R/PlLWnsRJcpQuvxrlr71Ab0Gl0r/g yCUbkzUr9DQXvBlG7STLjsnFeql70rUCYRhVNXo5P9Gd5NRMXopOXF68LZg0JtLbDj NWDsTld22BYYdo8O+Vk07IJEW02ZwlwcdChvtN2kzeHNXcIDL0mt9ZFToQ/iPeAFMS FGhfCRqW9/t3Jn7umP3x8hpJMQ+gNd+0TD6+cH0YIKQMIROMhf40SlprUdwNv8QkXz HpLc51HwA2u3Q== Date: Wed, 8 Sep 2021 02:04:30 +0300 From: Leon Romanovsky To: "Michael S. Tsirkin" Cc: Chaitanya Kulkarni , Max Gurtovoy , hch@infradead.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, stefanha@redhat.com, israelr@nvidia.com, nitzanc@nvidia.com, oren@nvidia.com, linux-block@vger.kernel.org, axboe@kernel.dk Subject: Re: [PATCH v3 1/1] virtio-blk: add num_request_queues module parameter Message-ID: References: <20210902204622.54354-1-mgurtovoy@nvidia.com> <20210905111415-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210905111415-mutt-send-email-mst@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, Sep 05, 2021 at 11:15:16AM -0400, Michael S. Tsirkin wrote: > On Sun, Sep 05, 2021 at 01:20:24PM +0300, Leon Romanovsky wrote: > > On Sun, Sep 05, 2021 at 01:49:46AM -0700, Chaitanya Kulkarni wrote: > > > > > > On 9/5/2021 12:46 AM, Leon Romanovsky wrote: > > > > > +static unsigned int num_request_queues; > > > > > +module_param_cb(num_request_queues, &queue_count_ops, &num_request_queues, > > > > > + 0644); > > > > > +MODULE_PARM_DESC(num_request_queues, > > > > > + "Number of request queues to use for blk device. Should > 0"); > > > > > + > > > > Won't it limit all virtio block devices to the same limit? > > > > > > > > It is very common to see multiple virtio-blk devices on the same system > > > > and they probably need different limits. > > > > > > > > Thanks > > > > > > > > > Without looking into the code, that can be done adding a configfs > > > > > > interface and overriding a global value (module param) when it is set from > > > > > > configfs. > > > > So why should we do double work instead of providing one working > > interface from the beginning? > > > > Thanks > > > > > > > > > > The main way to do it is really from the hypervisor. This one > is a pretty blunt instrument, Max here says it's useful to reduce > memory usage of the driver. If that's the usecase then a global limit > seems sufficient. How memory will you reduce? It is worth to write it in the commit message. Thanks > > -- > MST >