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 3B011ED1 for ; Thu, 7 Dec 2023 06:38:44 +0000 (UTC) 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="F8SpE+xT" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701931124; 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=zWU3XhY3SGz8Nm4Q405d0erGPeXKkfHuFXSX394aJLk=; b=F8SpE+xTqNcOxnosIq2kwiHdPxTGD1nykvYX5r11gyU17crEKzI2QI07h0hPo8xtDY4duV L7oOYwh6Uw2oKRJWpEvRx62S/4qc78d2dKfLlGX8SSw053Erv9acqfOgCSrJ5qJmfvKYaT /NVlbHVBnMbNWoBQ4tQYbvCmtIy7VEY= Received: from mail-ej1-f70.google.com (mail-ej1-f70.google.com [209.85.218.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-298-1xbO7vR3MQCqfuQzlCVPQA-1; Thu, 07 Dec 2023 01:38:42 -0500 X-MC-Unique: 1xbO7vR3MQCqfuQzlCVPQA-1 Received: by mail-ej1-f70.google.com with SMTP id a640c23a62f3a-a0c510419caso27649166b.1 for ; Wed, 06 Dec 2023 22:38:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701931121; x=1702535921; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=zWU3XhY3SGz8Nm4Q405d0erGPeXKkfHuFXSX394aJLk=; b=pEIJXZxrGZFcuD+emilx0Df0XQIFNO7RA2dTWmthlFgqzjMZzYIgW25xHx9Z/KSbx6 s1Z27GJqR3iYK7nu9DvMGZVCoe7dLz+FIFsLyNj8rMCu33k8G9cmhsKmZQcfpHqGqNy6 8Ok/iQD276LFcuyocpAdybdoWx179THTmlwntefc7MBmomRsTY8shudw2wiYR3uAjF01 /bZhU0oJ2mySWhWGcZbSbmGMk7rLhzLet0QUHzTOeGNj8t2dL0RQULESFfiT6z7CQY+a e/RQiJwtj/2oh1K3H+QKqFCb1OGTZuzaeAoRztN1dYXPhuD+0zjHsrh217sTnI6il8uV ptHA== X-Gm-Message-State: AOJu0Yw9GujhI2JUgX4+q2cUbrsjvZi9hJWaf/dm6K0efOCuZMSh1BlQ XdeZ6p0X+v6I2AhNLiil2lwwtAfpTg+Pa208tsDvZGuNikl+TuTAGmV/MOQq3i/LYkTzKNMfb+I 7n8IfEhIsElRcHhPlyrjl/V1xK0I= X-Received: by 2002:a17:906:412:b0:a19:a1ba:8cdf with SMTP id d18-20020a170906041200b00a19a1ba8cdfmr1283529eja.125.1701931121419; Wed, 06 Dec 2023 22:38:41 -0800 (PST) X-Google-Smtp-Source: AGHT+IHhiBhaS+kmbU1JKx2cAFUfZmT6awaVyiVkat1D9D0v41JMF0DlUXomnGzVKOZQPNjGyvsaNQ== X-Received: by 2002:a17:906:412:b0:a19:a1ba:8cdf with SMTP id d18-20020a170906041200b00a19a1ba8cdfmr1283523eja.125.1701931121146; Wed, 06 Dec 2023 22:38:41 -0800 (PST) Received: from redhat.com ([2.55.11.67]) by smtp.gmail.com with ESMTPSA id s6-20020a170906c30600b00a1dee0289b4sm376148ejz.169.2023.12.06.22.38.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 22:38:40 -0800 (PST) Date: Thu, 7 Dec 2023 01:38:37 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: Li Feng , Jens Axboe , Paolo Bonzini , Stefan Hajnoczi , Xuan Zhuo , "open list:BLOCK LAYER" , open list , "open list:VIRTIO BLOCK AND SCSI DRIVERS" Subject: Re: [PATCH] virtio_blk: set the default scheduler to none Message-ID: <20231207013617-mutt-send-email-mst@kernel.org> References: <20231207043118.118158-1-fengli@smartx.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit On Thu, Dec 07, 2023 at 02:02:36PM +0800, Jason Wang wrote: > On Thu, Dec 7, 2023 at 12:33 PM Li Feng wrote: > > > > virtio-blk is generally used in cloud computing scenarios, where the > > performance of virtual disks is very important. The mq-deadline scheduler > > has a big performance drop compared to none with single queue. > > At least you can choose the scheduler based on if mq is supported or not? > > Thanks This is already the case: static struct elevator_type *elevator_get_default(struct request_queue *q) { if (q->tag_set && q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT) return NULL; if (q->nr_hw_queues != 1 && !blk_mq_is_shared_tags(q->tag_set->flags)) return NULL; return elevator_find_get(q, "mq-deadline"); } I guess I agree blk is typically kind of similar to loopback so none by default makes sense here same as for loopback. Stefan care to comment? -- MST