Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932942AbaLJTtE (ORCPT ); Wed, 10 Dec 2014 14:49:04 -0500 Received: from mga02.intel.com ([134.134.136.20]:57532 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932299AbaLJTtB (ORCPT ); Wed, 10 Dec 2014 14:49:01 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,553,1413270000"; d="scan'208";a="621770529" From: Sudeep Dutt To: Greg Kroah-Hartman Cc: Arnd Bergmann , Jonathan Corbet , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Dave Jiang , Nikhil Rao , Ashutosh Dixit , Sudeep Dutt Subject: [PATCH char-misc-next 00/13] misc: mic: SCIF driver Date: Wed, 10 Dec 2014 11:47:40 -0800 Message-Id: X-Mailer: git-send-email 1.8.2.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The Symmetric Communication Interface (SCIF (pronounced as skiff)) is a low level communications API across PCIe currently implemented for MIC. Currently SCIF provides inter-node communication within a single host platform, where a node is a MIC Coprocessor or Xeon based host. SCIF abstracts the details of communicating over the PCIe bus while providing an API that is symmetric across all the nodes in the PCIe network. An important design objective for SCIF is to deliver the maximum possible performance given the communication abilities of the hardware. SCIF has been used to implement an offload compiler runtime and OFED support for MPI implementations for MIC coprocessors. ==== SCIF API Components ==== The SCIF API has the following parts: 1. Connection establishment using a client server model 2. Byte stream messaging intended for short messages 3. Node enumeration to determine online nodes 4. Poll semantics for detection of incoming connections and messages 5. Memory registration to pin down pages 6. Remote memory mapping for low latency CPU accesses via mmap 7. Remote DMA (RDMA) for high bandwidth DMA transfers 8. Fence APIs for RDMA synchronization SCIF exposes the notion of a connection which can be used by peer processes on nodes in a SCIF PCIe "network" to share memory "windows" and to communicate. A process in a SCIF node initiates a SCIF connection to a peer process on a different node via a SCIF "endpoint". SCIF endpoints support messaging APIs which are similar to connection oriented socket APIs. Connected SCIF endpoints can also register local memory which is followed by data transfer using either DMA, CPU copies or remote memory mapping via mmap. SCIF supports both user and kernel mode clients which are functionally equivalent. ==== SCIF Performance for MIC ==== DMA bandwidth comparison between the TCP (over ethernet over PCIe) stack versus SCIF shows the performance advantages of SCIF for HPC applications and runtimes. Comparison of TCP and SCIF based BW Throughput (GB/sec) 8 + PCIe Bandwidth ****** + TCP ###### 7 + ************************************** SCIF %%%%%% | %%%%%%%%%%%%%%%%%%% 6 + %%%% | %% | %%% 5 + %% | %% 4 + %% | %% 3 + %% | % 2 + %% | %% | % 1 + + ###################################### 0 +++---+++--+--+-+--+--+-++-+--+-++-+--+-++-+- 1 10 100 1000 10000 100000 Transfer Size (KBytes) SCIF allows memory sharing via mmap(..) between processes on different PCIe nodes and thus provides bare-metal PCIe latency. The round trip SCIF mmap latency from the host to an x100 MIC for an 8 byte message is 0.44 usecs. For more information on SCIF please refer to the Linux Con 2013 slides titled "Intel® MIC x100 Coprocessor Driver - on the Frontiers of Linux & HPC" at http://events.linuxfoundation.org/sites/events/files/slides/LinuxConMicDriver.pdf The talk can also be viewed at https://www.youtube.com/watch?v=dylbmmQs4W0 This initial patch series introduces the SCIF API and implements the SCIF connection, messaging and node enumeration APIs. SCIF poll, mmap, RDMA and fence APIs will be submitted in a future patch series once the initial base patches are accepted upstream. This patch series is divided into 13 patches as follows: 1) SCIF header file documenting the API along with the IOCTL interface 2) SCIF ring buffer is a single producer, single consumer byte stream ring buffer optimized for avoiding reads across the PCIe bus. The ring buffer is used to implement a receive queue for SCIF driver messaging between nodes and for byte stream messaging between SCIF endpoints. Each SCIF node has a receive queue for every other SCIF node, and each connected endpoint has a receive queue for messages from its peer. This pair of receive queues is referred to as a SCIF queue pair. 3) SCIF hardware bus which abstracts the low level hardware details so that the same SCIF driver can work without any changes on the host or the card as long as the hardware bus operations are implemented. 4) SCIF peer bus is used to register and unregister SCIF peer devices internally by the SCIF driver to signify the addition and removal of peer nodes respectively from the SCIF network. This simplifies remote node handling within SCIF and will also be used to support device probe/remove for SCIF client drivers (e.g. netdev over SCIF) 5) Common MIC header file changes to enable SCIF 6) SCIF module initialization, DMA/remote memory mapping APIs and debugfs hooks. 7) SCIF node queue pair setup sets up the kernel mode private node queue pairs between all the nodes to enable internal control message communication. 8) SCIF character device file operations and kernel APIs for opening and closing a user and kernel mode SCIF endpoint. This patch also enables binding to a SCIF port and listening for incoming SCIF connections. 9) SCIF connection APIs which establish a SCIF connection between a pair of user or kernel mode endpoints. 10) SCIF messaging APIs which allow sending messages between the SCIF endpoints via a byte stream based ring buffer which has been optimized to avoid reads across PCIe. The node enumeration API enables a user to query for the number of online nodes. 11) MIC host driver specific changes to enable SCIF 12) MIC card driver specific changes to enable SCIF 13) Add support for loading/unloading SCIF driver Nikhil Rao (1): misc: mic: SCIF connections APIs i.e. accept and connect Sudeep Dutt (12): misc: mic: SCIF header file and IOCTL interface misc: mic: SCIF ring buffer infrastructure misc: mic: SCIF Hardware Bus misc: mic: SCIF Peer Bus misc: mic: Common MIC header file changes in preparation for SCIF misc: mic: SCIF module initialization misc: mic: SCIF node queue pair setup management misc: mic: SCIF open close bind and listen APIs misc: mic: SCIF messaging and node enumeration APIs misc: mic: MIC host driver specific changes to enable SCIF misc: mic: MIC card driver specific changes to enable SCIF misc: mic: add support for loading/unloading SCIF driver Documentation/mic/mic_overview.txt | 28 +- Documentation/mic/scif_overview.txt | 62 ++ drivers/misc/mic/Kconfig | 40 +- drivers/misc/mic/Makefile | 3 +- drivers/misc/mic/bus/Makefile | 1 + drivers/misc/mic/scif/Makefile | 15 + include/uapi/linux/Kbuild | 1 + drivers/misc/mic/bus/scif_bus.h | 129 ++++ drivers/misc/mic/card/mic_device.h | 11 +- drivers/misc/mic/card/mic_x100.h | 1 + drivers/misc/mic/common/mic_dev.h | 3 + drivers/misc/mic/host/mic_device.h | 11 +- drivers/misc/mic/host/mic_intr.h | 3 +- drivers/misc/mic/host/mic_smpt.h | 1 + drivers/misc/mic/scif/scif_epd.h | 160 ++++ drivers/misc/mic/scif/scif_main.h | 250 +++++++ drivers/misc/mic/scif/scif_map.h | 113 +++ drivers/misc/mic/scif/scif_nodeqp.h | 182 +++++ drivers/misc/mic/scif/scif_peer_bus.h | 63 ++ drivers/misc/mic/scif/scif_rb.h | 100 +++ include/linux/scif.h | 1132 ++++++++++++++++++++++++++++ include/uapi/linux/mic_common.h | 12 + include/uapi/linux/scif_ioctl.h | 233 ++++++ drivers/misc/mic/bus/scif_bus.c | 210 ++++++ drivers/misc/mic/card/mic_device.c | 132 +++- drivers/misc/mic/card/mic_x100.c | 61 +- drivers/misc/mic/host/mic_boot.c | 264 ++++++- drivers/misc/mic/host/mic_debugfs.c | 13 + drivers/misc/mic/host/mic_main.c | 6 + drivers/misc/mic/host/mic_smpt.c | 7 +- drivers/misc/mic/host/mic_virtio.c | 6 +- drivers/misc/mic/host/mic_x100.c | 3 +- drivers/misc/mic/scif/scif_api.c | 1270 ++++++++++++++++++++++++++++++++ drivers/misc/mic/scif/scif_debugfs.c | 82 +++ drivers/misc/mic/scif/scif_epd.c | 353 +++++++++ drivers/misc/mic/scif/scif_fd.c | 303 ++++++++ drivers/misc/mic/scif/scif_main.c | 395 ++++++++++ drivers/misc/mic/scif/scif_nm.c | 229 ++++++ drivers/misc/mic/scif/scif_nodeqp.c | 1303 +++++++++++++++++++++++++++++++++ drivers/misc/mic/scif/scif_peer_bus.c | 124 ++++ drivers/misc/mic/scif/scif_ports.c | 124 ++++ drivers/misc/mic/scif/scif_rb.c | 248 +++++++ Documentation/mic/mpssd/mpss | 23 +- 43 files changed, 7654 insertions(+), 56 deletions(-) create mode 100644 Documentation/mic/scif_overview.txt create mode 100644 drivers/misc/mic/scif/Makefile create mode 100644 drivers/misc/mic/bus/scif_bus.h create mode 100644 drivers/misc/mic/scif/scif_epd.h create mode 100644 drivers/misc/mic/scif/scif_main.h create mode 100644 drivers/misc/mic/scif/scif_map.h create mode 100644 drivers/misc/mic/scif/scif_nodeqp.h create mode 100644 drivers/misc/mic/scif/scif_peer_bus.h create mode 100644 drivers/misc/mic/scif/scif_rb.h create mode 100644 include/linux/scif.h create mode 100644 include/uapi/linux/scif_ioctl.h create mode 100644 drivers/misc/mic/bus/scif_bus.c create mode 100644 drivers/misc/mic/scif/scif_api.c create mode 100644 drivers/misc/mic/scif/scif_debugfs.c create mode 100644 drivers/misc/mic/scif/scif_epd.c create mode 100644 drivers/misc/mic/scif/scif_fd.c create mode 100644 drivers/misc/mic/scif/scif_main.c create mode 100644 drivers/misc/mic/scif/scif_nm.c create mode 100644 drivers/misc/mic/scif/scif_nodeqp.c create mode 100644 drivers/misc/mic/scif/scif_peer_bus.c create mode 100644 drivers/misc/mic/scif/scif_ports.c create mode 100644 drivers/misc/mic/scif/scif_rb.c -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/