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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 A468AC46471 for ; Mon, 6 Aug 2018 12:27:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1CCE3208A2 for ; Mon, 6 Aug 2018 12:27:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CCE3208A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ucw.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730528AbeHFOga (ORCPT ); Mon, 6 Aug 2018 10:36:30 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:36777 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726901AbeHFOga (ORCPT ); Mon, 6 Aug 2018 10:36:30 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id 5D0C8806AF; Mon, 6 Aug 2018 14:27:34 +0200 (CEST) Date: Mon, 6 Aug 2018 14:27:33 +0200 From: Pavel Machek To: Kenneth Lee Cc: Jonathan Corbet , Herbert Xu , "David S . Miller" , Joerg Roedel , Alex Williamson , Kenneth Lee , Hao Fang , Zhou Wang , Zaibo Xu , Philippe Ombredanne , Greg Kroah-Hartman , Thomas Gleixner , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-accelerators@lists.ozlabs.org, Lu Baolu , Sanjay Kumar , linuxarm@huawei.com Subject: Re: [RFC PATCH 1/7] vfio/spimdev: Add documents for WarpDrive framework Message-ID: <20180806122733.GA17232@xo-6d-61-c0.localdomain> References: <20180801102221.5308-1-nek.in.cn@gmail.com> <20180801102221.5308-2-nek.in.cn@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180801102221.5308-2-nek.in.cn@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > WarpDrive is a common user space accelerator framework. Its main component > in Kernel is called spimdev, Share Parent IOMMU Mediated Device. It exposes spimdev is really unfortunate name. It looks like it has something to do with SPI, but it does not. > +++ b/Documentation/warpdrive/warpdrive.rst > @@ -0,0 +1,153 @@ > +Introduction of WarpDrive > +========================= > + > +*WarpDrive* is a general accelerator framework built on top of vfio. > +It can be taken as a light weight virtual function, which you can use without > +*SR-IOV* like facility and can be shared among multiple processes. > + > +It can be used as the quick channel for accelerators, network adaptors or > +other hardware in user space. It can make some implementation simpler. E.g. > +you can reuse most of the *netdev* driver and just share some ring buffer to > +the user space driver for *DPDK* or *ODP*. Or you can combine the RSA > +accelerator with the *netdev* in the user space as a Web reversed proxy, etc. What is DPDK? ODP? > +How does it work > +================ > + > +*WarpDrive* takes the Hardware Accelerator as a heterogeneous processor which > +can share some load for the CPU: > + > +.. image:: wd.svg > + :alt: This is a .svg image, if your browser cannot show it, > + try to download and view it locally > + > +So it provides the capability to the user application to: > + > +1. Send request to the hardware > +2. Share memory with the application and other accelerators > + > +These requirements can be fulfilled by VFIO if the accelerator can serve each > +application with a separated Virtual Function. But a *SR-IOV* like VF (we will > +call it *HVF* hereinafter) design is too heavy for the accelerator which > +service thousands of processes. VFIO? VF? HVF? Also "gup" might be worth spelling out. > +References > +========== > +.. [1] Accroding to the comment in in mm/gup.c, The *gup* is only safe within > + a syscall. Because it can only keep the physical memory in place > + without making sure the VMA will always point to it. Maybe we should > + raise the VM_PINNED patchset (see > + https://lists.gt.net/linux/kernel/1931993) again to solve this probl I went through the docs, but I still don't know what it does. Pavel