85 lines
3.5 KiB
ReStructuredText
85 lines
3.5 KiB
ReStructuredText
.. _smp_pktqueue:
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SMP pktqueue
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############
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Overview
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********
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This sample application performs a simplified network layer forwarding function
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(essentially checksum calculation from IP Header Validation) of the Internet protocol
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suite specified in RFC1812 "Requirements for IP Version 4 Routers" which
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can be found at http://www.faqs.org/rfcs/rfc1812.html. This application
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provides an indication of the potential performance of a microprocessor in an
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IP router system.
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At the beginning of the application the array (size defined in SIZE_OF_QUEUE)
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of packet headers is initialized. Each header contains some random data of size
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defined in SIZE_OF_HEADER and calculated crc16 header checksum
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in appropriate field defined by CRC_BYTE_1 and CRC_BYTE_2. The contents of
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header follows:
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| 0 - 3 | 4 - 7 | 8 - 15 | 16 - 31 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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|Version| IHL |Type of Service| Total Length |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Identification |Flags| Fragment Offset |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Time to Live | Protocol | Header Checksum |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Source Address |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Destination Address |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Options | Padding |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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The headers then are stored in multiple "sender" queues (the number is defined
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in QUEUE_NUM). After that for each pair of "sender"/"receiver" queues one thread
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is created, which will control "sender" queue processing.
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Then in each queue-related thread several(defined in THREADS_NUM) threads are created. Each
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of them first pick the header from "sender" queue, calculates crc and if
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crc is correct put the header to "receiver" queue. Only one thread in a
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time can access to sender or receiver queue.
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As soon as all headers in each pair of queues are moved from "sender" to
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"receiver" queue the execution of threads(related to pair) are terminated.
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By changing the value of CONFIG_MP_MAX_NUM_CPUS on SMP systems, you
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can see that using more cores takes almost linearly less time
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to complete the computational task.
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You can also edit the sample source code to change the
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number of parallel executed pairs of queues(``QUEUE_NUM``),
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the number of threads per pair of queues(``THREADS_NUM``),
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the number of headers in queue (``SIZE_OF_QUEUE``), and
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size of header in bytes (``SIZE_OF_HEADER``).
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Building and Running
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********************
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This project outputs total time required for processing all packet headers.
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It can be built and executed on QEMU as follows:
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.. zephyr-app-commands::
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:zephyr-app: samples/arch/smp/pktqueue
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:host-os: unix
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:board: qemu_x86_64
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:goals: run
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:compact:
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Sample Output
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=============
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.. code-block:: console
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Simulating IP header validation on multiple cores.
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Each of 2 parallel queues is processed by 3 threads on 2 cores and contain 5000 packet headers.
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Bytes in packet header: 24
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RESULT: OK
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Application ran successfully.
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All 20000 packet headers were processed in 89 msec
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