From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (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 1725F1D688 for ; Mon, 17 Jun 2024 02:34:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718591645; cv=none; b=FgF0EqRVQVfLQGcoD1zzuamuxHvBEDZvdwDwVQWUJrx3XfDzA2kI3u6e4iameYk+i18MjmRLGZMpSGf0scrTnOlEc9c5Y2JFvY/3py2OvCkJbQ2cEzkes3hqB72rc/uevHxg74kC+tCPZK1xoRRXVDCrESIpkaO2gHPevE8eCfE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718591645; c=relaxed/simple; bh=M9B5/Q61qJpuT00ABATHdhBEN8Z1dLc93B6uQP4cWHs=; h=Message-ID:Subject:Date:From:To:Cc:References:In-Reply-To; b=UdfBJ1xv1b+m0uR0PdKo4LbQ3r7kn2DV7/5BCNMvZIgTMLP7cRbuxCJiqGV/61KAisqYRKJpH5tJBwCXO1yLPiecpYsqYol1w3ZJcYtR9ViIdXhOH9gyolWQhowC8SZMdTi24ELT4VeQQ0ykT9k/Hpt23+pc0Jt2KfcMYFCsrE4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=JYW7hZtS; arc=none smtp.client-ip=115.124.30.119 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="JYW7hZtS" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1718591640; h=Message-ID:Subject:Date:From:To; bh=+hD5aiRp9vD/Q5h4CTGwtF4B64D1hjiJLeMDwvT0eDA=; b=JYW7hZtSTxSNtj15rOXUj5QNVBmaJXAxj9deTRFjFbi1be70QhYqH1gGzbay4Ub/5j+GvBvxmVfRCMRGLGi3oweGgGCFF0i5SARul9Ygr+Rf0oFr7agDZH85JaRPtWnBPJ+bMdVW17jE825mnrzU2TdfbHB6VsTsadeuSJTDN4k= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R851e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037067110;MF=hengqi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0W8X5fUM_1718591639; Received: from localhost(mailfrom:hengqi@linux.alibaba.com fp:SMTPD_---0W8X5fUM_1718591639) by smtp.aliyun-inc.com; Mon, 17 Jun 2024 10:33:59 +0800 Message-ID: <1718591277.4770932-5-hengqi@linux.alibaba.com> Subject: Re: [PATCH v5] virtio-net: clarify coalescing parameters settings Date: Mon, 17 Jun 2024 10:27:57 +0800 From: Heng Qi To: "Michael S. Tsirkin" Cc: Halil Pasic , Cornelia Huck , "virtio-comment@lists.linux.dev" , Jason Wang , Xuan Zhuo , Parav Pandit References: <20240528044702.50603-1-hengqi@linux.alibaba.com> <20240607220246.3213607c.pasic@linux.ibm.com> <1717814062.4461155-1-hengqi@linux.alibaba.com> <20240610144602.57a04723.pasic@linux.ibm.com> <1718026545.7557275-2-hengqi@linux.alibaba.com> <20240610221900.1810ea96.pasic@linux.ibm.com> <1718102433.0456574-3-hengqi@linux.alibaba.com> <20240611122756-mutt-send-email-mst@kernel.org> <20240613021132-mutt-send-email-mst@kernel.org> In-Reply-To: <20240613021132-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: virtio-comment@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: On Thu, 13 Jun 2024 02:13:50 -0400, "Michael S. Tsirkin" wrote: > On Tue, Jun 11, 2024 at 05:43:18PM +0000, Parav Pandit wrote: > > > > > > > From: Michael S. Tsirkin > > > Sent: Tuesday, June 11, 2024 10:00 PM > > > > > > > How we can we make progress with > > > the realease but sure we don't make backwards compat a pain? > > > > > > Ideas? > > > > > There is no functional break with this relaxation. > > Device set some non-zero defaults and driver didn't modify them.... > > Anything broken? Unlikely. > > And device/driver has better performance, is that a problem? Unlikely. > > Sorry, my vacation just ended. > > Yes, it is possible. Driver can cache values it sets > and never query device with get. Don't we already have a lot of behaviors to drive queries from devices? RSS context, device stats. > Before anything is set, driver will report incorrect values. Devices that are widely supported and supported by good practices should have any initialization value. Just reporting 0 is incorrect value. Although the spec now says so. > What will break as a result? Hard to predict. > > > Given the patch is big, I am inclined to say it just should use > a feature bit. > This doesn't seem to break anything in my opinion, we just told the device that now you can set more values. Using new feature bits does not seem necessary. Thanks. > -- > MST >