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 70AD42F2A; Mon, 10 Feb 2025 05:09:00 +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=1739164145; cv=none; b=eWsm3oCiHIu/dwk1tde6Z8PKzBUcgCc1Pq2Yg2fmz6HSv8aSNa4zWtQ5R6KPwY/I6Gc0Q/ZmtTW6OZBa37Vs3gxSYJMlNDfF9ZQaiRJkpCiGbl/LaQatcrIjyTEoUK1h1cUpO2omr0Fz55Pa29ZNArP/TplRLqK7oOIgkzwyFyo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739164145; c=relaxed/simple; bh=GrGoLPWTuqbFu04kHEX8uIkan9MVGKWMGiOqmDkaD7E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QaI2AxGGmsfuDtKmhI98mjkc7HpaqQXcLlHS1/1AOsM/NnNAM2yg0ywC2+4xJoCIP1XRGqmy7r/Embd4bFvTmCQ23zg7naKyT2NvvL58uBUF+yVJfjaZCmHZWlY4xccjV3fBg+TBMaftjWbIqh1CgHvake26+SYGmeApT4iWBz8= 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=KboGDcVd; 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="KboGDcVd" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1739164133; h=Date:From:To:Subject:Message-ID:MIME-Version:Content-Type; bh=0lJ80j8f4PuDCGx2UI8jp4JUqbAEwGpMW2Sj3lGEKFs=; b=KboGDcVdgyJzwG4VHW+/fhC1SioSc6zZ8YdGFFoKRCuWZ8qTkmgyTknRyxCI2OqzHzgfjeQVf5Zeo3dMl1F5+fD73/TUvOefEigyPEAQzUNNOtaXpi69MAyCDQuWYAOB81jtbnDFCm9PGFSt2XJL+sD6hjtTtQfjY8655jow+co= Received: from localhost(mailfrom:dust.li@linux.alibaba.com fp:SMTPD_---0WP4wzUG_1739164131 cluster:ay36) by smtp.aliyun-inc.com; Mon, 10 Feb 2025 13:08:52 +0800 Date: Mon, 10 Feb 2025 13:08:51 +0800 From: Dust Li To: Alexandra Winter , Niklas Schnelle , Julian Ruess , Wenjia Zhang , Jan Karcher , Gerd Bayer , Halil Pasic , "D. Wythe" , Tony Lu , Wen Gu , Peter Oberparleiter , David Miller , Jakub Kicinski , Paolo Abeni , Eric Dumazet , Andrew Lunn Cc: Thorsten Winkler , netdev@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Simon Horman Subject: Re: [RFC net-next 0/7] Provide an ism layer Message-ID: <20250210050851.GS89233@linux.alibaba.com> Reply-To: dust.li@linux.alibaba.com References: <20250115195527.2094320-1-wintera@linux.ibm.com> <20250116093231.GD89233@linux.alibaba.com> <0f96574a-567e-495a-b815-6aef336f12e6@linux.ibm.com> <20250117021353.GF89233@linux.alibaba.com> <20250118153154.GI89233@linux.alibaba.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On 2025-01-28 17:04:53, Alexandra Winter wrote: > > >On 18.01.25 16:31, Dust Li wrote: >> On 2025-01-17 11:38:39, Niklas Schnelle wrote: >>> On Fri, 2025-01-17 at 10:13 +0800, Dust Li wrote: >>>>> >>> ---8<--- >>>>> Here are some of my thoughts on the matter: >>>>>>> >>>>>>> Naming and Structure: I suggest we refer to it as SHD (Shared Memory >>>>>>> Device) instead of ISM (Internal Shared Memory). >>>>> >>>>> >>>>> So where does the 'H' come from? If you want to call it Shared Memory _D_evice? >>>> >>>> Oh, I was trying to refer to SHM(Share memory file in the userspace, see man >>>> shm_open(3)). SMD is also OK. >>>> >>>>> >>>>> >>>>> To my knowledge, a >>>>>>> "Shared Memory Device" better encapsulates the functionality we're >>>>>>> aiming to implement. >>>>> >>>>> >>>>> Could you explain why that would be better? >>>>> 'Internal Shared Memory' is supposed to be a bit of a counterpart to the >>>>> Remote 'R' in RoCE. Not the greatest name, but it is used already by our ISM >>>>> devices and by ism_loopback. So what is the benefit in changing it? >>>> >>>> I believe that if we are going to separate and refine the code, and add >>>> a common subsystem, we should choose the most appropriate name. >>>> >>>> In my opinion, "ISM" doesn’t quite capture what the device provides. >>>> Since we’re adding a "Device" that enables different entities (such as >>>> processes or VMs) to perform shared memory communication, I think a more >>>> fitting name would be better. If you have any alternative suggestions, >>>> I’m open to them. >>> >>> I kept thinking about this a bit and I'd like to propose yet another >>> name for this group of devices: Memory Communication Devices (MCD) >>> >>> One important point I see is that there is a bit of a misnomer in the >>> existing ISM name in that our ISM device does in fact *not* share >>> memory in the common sense of the "shared memory" wording. Instead it >>> copies data between partitions of memory that share a common >>> cache/memory hierarchy while not sharing the memory itself. loopback- >>> ism and a possibly future virtio-ism on the other hand would share >>> memory in the "shared memory" sense. Though I'd very much hope they >>> will retain a copy mode to allow use in partition scenarios. >>> >>> With that background I think the common denominator between them and >>> the main idea behind ISM is that they facilitate communication via >>> memory buffers and very simple and reliable copy/share operations. I >>> think this would also capture our planned use-case of devices (TTYs, >>> block devices, framebuffers + HID etc) provided by a peer on top of >>> such a memory communication device. >> >> Make sense, I agree with MCD. >> >> Best regard, >> Dust >> > > Hi Winter, Sorry for the late reply; we were on break for the Chinese Spring Festival. > >In the discussion with Andrew Lunn, it showed that >a) we need an abstract description of 'ISM' devices (noted) >b) DMBs (Direct Memory Buffers) are a critical differentiator. > >So what do your think of Direct Memory Communication (DMC) as class name for these devices? > >I don't have a strong preference (we could also stay with ISM). But DMC may be a bit more >concrete than MCD or ISM. I personally prefer MCD over Direct Memory Communication (DMC). For loopback or Virtio-ISM, DMC seems like a good choice. However, for IBM ISM, since there's a DMA copy involved, it doesn’t seem truly "Direct," does it? Additionally, since we are providing a device, MCD feels like a more fitting choice, as it aligns better with the concept of a "device." Best regards, Dust