Abaco's Point to Point Communication API
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README.md

README.md

Takyon Logo

License

Copyright 2018 Abaco Systems Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

About

Takyon is a high level, high speed, portable, dynamic, fully scalable, point to point, message passing, communication API. It's focused on the embedded HPC industry, with no intention to compete with MPI which is focused on the HPC industry. Like MPI, Takyon is designed to be a wrapper over many low level point to point communication APIs and look like a single high level message passing API. This is to provide an application with a one stop shop for all point to point message passing needs no mater the interconnect or locality (inter-thread, inter-process, inter-processor, intra-application, inter-application). Here's a hello world example that could work with any interconnect and any locality:

// Sender
TakyonPathAttributes attrs = takyonAllocAttributes(is_endpointA, is_polling, nbufsAtoB, nbufsBtoA, max_bytes, TAKYON_WAIT_FOREVER, "Socket -client 192.168.35.23 -port 12345");
TakyonPath *path = takyonCreate(&attrs);
char *data_addr = (char *)path->attrs.sender_addr_list[buffer];
uint64_t nbytes = 1 + (uint64_t)sprintf(data_addr, "%s", "Hello World!");
takyonSend(path, buffer, nbytes, 0/*soffset*/, 0/*doffset*/, NULL/*&timed_out*/);
if (path->attrs.send_completion_method == TAKYON_USE_SEND_TEST) takyonSendTest(path, buffer, NULL/*&timed_out*/);
takyonDestroy(&path);

// Receiver
TakyonPathAttributes attrs = takyonAllocAttributes(!is_endpointA, is_polling, nbufsAtoB, nbufsBtoA, max_bytes, TAKYON_WAIT_FOREVER, "Socket -server Any -port 12345");
TakyonPath *path = takyonCreate(&attrs);
takyonRecv(path, buffer, NULL/*&bytes_received*/, NULL/*&offset*/, NULL/*&timed_out*/);
char *data_addr = (char *)(path->attrs.recver_addr_list[buffer] + offset);
printf("Message from sender: %s\n", data_addr);
takyonDestroy(&path);

To change to a different locality/interconnect, just modify "Socket ..." with any supported interconnect.

Mission Statement

The flexibility and performance of low level. The simplicity of high level.

Documentation

For all the great details on Takyon, read the following PDFs in Takyon's docs/ folder:

  • Takyon Reference Sheet.pdf - All the details at a quick glance.
  • Takyon Users Guide.pdf - In depth details of the design and how to use the API.

This readme documents the supported operating systems and interconnects for Abaco's reference implementation of Takyon. It provides instructions on how to build the libraries and the examples. Refer to the example specific readme files to determine how to run each example.

Supported OSes

Linux

  • Tested on Ubuntu 16.04 64-bit Intel using gcc, but should work on most other Linux flavors and chip architectures.
  • All interconnects are supported

Mac

  • Tested on OSX 10.13 64-bit using gcc
  • All interconnects are supported

Windows

  • Tested on Window 10 64-bit using MSVC 2015 & 2017
  • All interconnects are supported

Build Instructions

Linux

> cd Takyon/API/builds/linux_intel_64bit
> make

This creates:

libTakyon.a
libTakyonMemcpy.so
libTakyonMmap.so
libTakyonSocket.so

Mac OSX

> cd Takyon/API/builds/mac_intel_64bit
> make

This creates:

libTakyon.a
libTakyonMemcpy.so
libTakyonMmap.so
libTakyonSocket.so

Windows

> cd Takyon\API\builds\windows_intel_64bit
> nmake

This creates:

  • Takyon.lib

Preparing to Run Examples

Linux

> export TAKYON_LIBS="<Takyon_parent_folder>/Takyon/API/builds/linux_intel_64bit"

Mac OSX

> export TAKYON_LIBS="<Takyon_parent_folder>/Takyon/API/builds/mac_intel_64bit"

Windows

All features are encapsulated in the static library Takyon.lib, so no environment variable is needed.

Supported Interconnects

This reference implementation supports commonly used mechanisms for inter-thread, inter-process and inter-processor communication. Abaco's upcoming commercial implementation will support additional inter-processor and GPU communication protocols including RDMA and GPU IPC.

Memcpy

  • Endpoints must be in the same process but different threads.
  • Uses Posix mutexes and conditional variables to handle atomic coordination.
  • Application can optionally pass in sender and/or receiver memory, otherwise it will be allocated by Takyon.
  • If -share option is used:
    • Both endpoints will share the memory buffers for a particular direction (AtoB and BtoA are different directions). This is an advanced feature.
    • Application can optionally pass in sender or receiver memory (but not both), otherwise it will be allocated by Takyon.

Mmap

  • Endpoints must be in the same OS but different processes.
  • Uses Posix memory map for data memory that is accessible between processes.
  • On unix, uses process shared Posix mutexes and conditional variables to handle atomic coordination. On Windows, uses processed based Mutex and Events.
  • Uses local sockets for connecting, disconnecting, and detecting disconnections.
  • Application can optionally pass in sender memory, otherwise it will be allocated by Takyon.
  • Application can optionally pass in pre-allocated named memory maps, otherwise it will be allocated by Takyon. In order to allow this, the interconnect flag -app_alloced_recv_mmap must be set on the endpoint that allocates the named memory maps. The remote endpoint must then set the flag -remote_mmap_prefix <prefix-name>, where <prefix-name><buffer_index> is the name used when the memory mapped buffers were created. This is helpful when multiple communication paths are used to gather data into a contiguous buffer.
  • If -share option is used:
    • Both endpoints will share the memory buffers for a particular direction (AtoB and BtoA are different directions). This is an advanced feature.

Socket

  • Endpoints can be in the same OS or different OSes, but in the same IP network.
  • Can use local sockets (if in the same OS only) or TCP sockets. If using local sockets, on Linux and Mac, it will use a local Unix socket which will have better performance than using a TCP socket with IP address 127.0.0.1. On Windows it uses 127.0.0.1 with a TCP connection since local Unix sockets do not exist on Windows.
  • The socket option "TCP No delay" is turned on to improve latency.
  • If polling is used (i.e. attrs.is_polling = true), sockets do not require both endpoints to be polling.

SocketDatagram

  • Endpoints can be in the same OS or different OSes, but in the same IP network. Only are independent of each other. Remote endpoint does not need to be a Takyon endpoint. Also used for UDP enabled IO devices.
  • Is used for UDP connectionless transfers (good for live-streaming and multicasting)
  • Endpoint A is always a sender and endpoint B is always a receiver.

Interconnect Specifications

These are the text strings passed into attributes->interconnect[]

Connected Specifications (two sided)

These are reliable two-way connections where both endpoints must be created together to allow for transfers.

  • Inter-thread (endpoints in the same process)
    Memcpy -ID <ID> [-share]
  • Inter-process (endpoints in the same OS)
    Mmap -ID <ID> [-share] [-reuse] [-app_alloced_recv_mmap] [-remote_mmap_prefix <name>]
    Socket -local -ID <ID> [-reuse]
    Socket -client 127.0.0.1 -port <port>
    Socket -server 127.0.0.1 -port <port> [-reuse]
    Socket -server Any -port <port> [-reuse]
  • Inter-processor (endpoints not in the same OS)
    Socket -client <IP> -port <port>
    Socket -server <IP> -port <port> [-reuse]
    Socket -server Any -port <port> [-reuse]

Bi-Directional Parameter Descriptions

  • -ID <ID>
    Can be any integer
  • -share
    Sender and receiver share the same buffers. Don't put data in the sender buffer until the receiver is done processing on the buffer.
  • -app_alloced_recv_mmap
    Informs the path that all of the receive buffers where allocated by the application using a named memory map.
  • -remote_mmap_prefix <name>
    If the remote endpoint is using an application allocated named memory map for the buffers, this defines the name used to create the memory maps.
  • -local
    Uses a Unix local socket which is better performance due to avoid some of the TCP stack
  • -client 127.0.0.1
    The client side of the connection. 127.0.0.1 is a special loop back address used to keep communication local (in the same OS). This uses the full TCP stack so it's not as efficient as using -local.
  • -server 127.0.0.1
    The server side of the loop back connection.
  • -port <port>
    Use a valid port number not being blocked by a firewall and not used by another service. This must be the same on both endpoints.
  • -client <IP>
    The client side of the TCP connection. The IP address must be the same as the server side (-server side).
  • -server <IP>
    The server side of the TCP connection. The IP address must be the same as the client side (-client side).
  • -server Any
    The server side of the TCP connection. This allows the connection to occur on any IP interface that is listening on the specified port number. Since the client side must specify an IP address, this inherently defines the IP interface that will be used on the server side. Be careful to avoid multiple interfaces using the same port number.
  • -reuse
    In the case where a socket connection is shut down and then reused, it may not be usable immediately due to a socket timed wait state. If this occurs, then use this flag to allow the socket address to be reused.

Connectionless Specifications (one sided)

These are one sided connections where only one side needs to be created to allow for unreliable UDP (user datagram protocol) transfers. Typically good for live-streaming services and IO devices where it's OK to periodically drop data.

  • Inter-process & inter-processor
    SocketDatagram -unicastSend -client <IP> -port <port>
    SocketDatagram -unicastRecv -server <IP> -port <port> [-reuse]
    SocketDatagram -multicastSend -server <IP> -group <IP> -port <port> [-disable_loopback] [-TTL <n>]
    SocketDatagram -multicastRecv -server <IP> -group <IP> -port <port> [-reuse]

Connectionless Parameter Descriptions

  • -client <IP>
    The sender side of a UDP connection. The IP address must be where the datagrams will be sent to.
  • -server <IP>
    The IP addr of the local interface of the UDP connection. If this is a unicast, then the IP address can be 'Any' which will listen for activity on any interface for the specified port number.
  • -group <IP>
    The multicast group to join. The IP address must be in the range 224.0.0.0 through 239.255.255.255. Some are reserved so make sure to use an unused address.
  • -port <port>
    Use a valid port number not being blocked by a firewall and not used by another service. This must be the same on both endpoints.
  • -reuse
    In the case where a socket connection is shut down and then reused, it may not be usable immediately due to a socket timed wait state. If this occurs, then use this flag to allow the socket address to be reused.
  • -disable_loopback
    By default, a multicast sender will also transfer the datagram to itself. Use this flag to stop this.
  • -TTL <n>
    This defines how far down the network the multicast datagram will be sent: 0: Restricted to the same host 1: Restricted to the same subnet (this is the default value if the -TTL flag is not specified) 32: Restricted to the same site 64: Restricted to the same region 128: Restricted to the same continent 255: Unrestricted in scope

Application Header Files

These will be needed by Takyon applications:

  • Core APIs: Takyon/API/inc/takyon.h
  • Open Source Extension APIs: Takyon/extensions/takyon_extensions.h

Running the Examples

  • The examples are found in Takyon/examples/
  • Each example has a README.txt which explains what is does and how to build and run.

Overview of the Examples

  • hello_world_mt: The most basic Takyon application, specifically for two threads in a single process.
  • hello_world_mp: The most basic Takyon application, specifically for two processes (both are not required to be on the same processor).
  • hello_world_graph: The most basic Takyon application, designed to use the graph extension functions to make it more like MPI.
  • performance: Calculates the latency and throughput of any supported interconnect.
  • determinism: Shows the determinism of an interconnect via multple trasfer times displayed in a histogram.
  • fault_tolerant: Shows that connections can be broken (via timeouts, cable disconnection, or control-C) then recover from the failure.
  • barrier: Uses the graph extension functions to create a pipeline and barrier collective, where the barrier is used to synchronize the pipeline processing.
  • reduce: Uses the graph extension functions to create a reduction collective. The app defines the reduction operation. The results can optionally be broadcast to all threads involved.
  • pipeline: Uses the graph extension functions to create a long data processing path by connecting a set of Takyon paths in series.
  • scatter_gather: Uses the graph extension functions to create a collective example similar to MPI.
  • connectionless: Shows how Takyon can also be used with one sided connectionless interconnects (including multicast), such as live streaming and IO devices like GigE cameras, Lidar, analog-to-digital and digital-to-analog.

The Evolution of Takyon

The Takyon API was formulated by Michael Both after about 20 years of challenging experiences with communication APIs for heterogeneous compute architectures in the embedded HPC industry. He implemented applications using many standard communication APIs (Socket, MPI, Verbs, Network Direct, named memory map, message queue, semaphore, mutex, cond var, memcpy, corba), many company proprietary APIs (Abaco, Mercury, Ixthos, Texas Instruments, Sparc, Sky Computers, Radstone Technologies, Google, Apple), and on many different architectures (Sparc, PPC, Sharc, TI, Intel, Arm, iOS, Android). In addition to using all these communication APIs, he also implemented one high level open standard (Abaco's MPI 1.x) and two high level proprietary APIs (Lockheed Martin's GEDAE and Abaco's AXIS Flow). This vast experience gave a great insight into the strengths and weaknesses of each communication API. One API did not fit all the needs of the common embedded HPC application, and it became clear that a better standard was needed for this audience. Khronos was first approached in 2017 to see if Takyon should become an open standard. In 2018 Khronos decided to create an exploratory group to determine industry interest.