diff options
Diffstat (limited to 'host/docs')
| -rw-r--r-- | host/docs/CMakeLists.txt | 1 | ||||
| -rw-r--r-- | host/docs/index.rst | 9 | ||||
| -rw-r--r-- | host/docs/transport.rst | 82 | ||||
| -rw-r--r-- | host/docs/usrp1.rst | 23 | ||||
| -rw-r--r-- | host/docs/usrp2.rst | 41 |
5 files changed, 88 insertions, 68 deletions
diff --git a/host/docs/CMakeLists.txt b/host/docs/CMakeLists.txt index bbb8812b0..65db3befc 100644 --- a/host/docs/CMakeLists.txt +++ b/host/docs/CMakeLists.txt @@ -25,6 +25,7 @@ SET(manual_sources dboards.rst general.rst images.rst + transport.rst usrp1.rst usrp2.rst ) diff --git a/host/docs/index.rst b/host/docs/index.rst index bd55edc0b..7f8129e2d 100644 --- a/host/docs/index.rst +++ b/host/docs/index.rst @@ -20,11 +20,12 @@ Building the UHD ^^^^^^^^^^^^^^^^^^^^^ Application Notes ^^^^^^^^^^^^^^^^^^^^^ -* `General App Notes <./general.html>`_ +* `General Application Notes <./general.html>`_ * `Firmware and FPGA Image Notes <./images.html>`_ -* `USRP1 App Notes <./usrp1.html>`_ -* `USRP2 App Notes <./usrp2.html>`_ -* `Daughterboard App Notes <./dboards.html>`_ +* `USRP1 Application Notes <./usrp1.html>`_ +* `USRP2 Application Notes <./usrp2.html>`_ +* `Daughterboard Application Notes <./dboards.html>`_ +* `Transport Application Notes <./transport.html>`_ ^^^^^^^^^^^^^^^^^^^^^ API Documentation diff --git a/host/docs/transport.rst b/host/docs/transport.rst new file mode 100644 index 000000000..30fc1d78f --- /dev/null +++ b/host/docs/transport.rst @@ -0,0 +1,82 @@ +======================================================================== +UHD - Transport Application Notes +======================================================================== + +.. contents:: Table of Contents + +The advanced user can pass optional parameters +into the underlying transport layer through the device address. +These optional parameters control how the transport object allocates memory, +resizes kernel buffers, spawns threads, etc. +When not spcified, the transport layer will use values for these parameters +that are known to perform well on a variety of systems. +The transport parameters are defined below for the various transports in the UHD: + +------------------------------------------------------------------------ +UDP transport (ASIO) +------------------------------------------------------------------------ +The UDP transport is implemented with Boost's ASIO library. +ASIO provides an asynchronous API for user-space sockets. +The transport implementation allocates a number of buffers +and submits asynchronous requests for send and receive. +IO service threads run in the background to process these requests. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Transport parameters +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +The following parameters can be used to alter the transport's default behavior: + +* **recv_frame_size:** The size of a single receive buffer in bytes +* **num_recv_frames:** The number of receive buffers to allocate +* **send_frame_size:** The size of a single send buffer in bytes +* **num_send_frames:** The number of send buffers to allocate +* **concurrency_hint:** The number of threads to run the IO service + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Resize socket buffers +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +It may be useful increase the size of the socket buffers to +move the burden of buffering samples into the kernel, or to +buffer incoming samples faster than they can be processed. +However, if your application cannot process samples fast enough, +no amount of buffering can save you. +The following parameters can be used to alter socket's buffer sizes: + +* **recv_buff_size:** The desired size of the receive buffer in bytes +* **send_buff_size:** The desired size of the send buffer in bytes + +**Note:** Large send buffers tend to decrease transmit performance. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Linux specific notes +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +On linux, the maximum buffer sizes are capped by the sysctl values +**net.core.rmem_max** and **net.core.wmem_max**. +To change the maximum values, run the following commands: +:: + + sudo sysctl -w net.core.rmem_max=<new value> + sudo sysctl -w net.core.wmem_max=<new value> + +Set the values permanently by editing */etc/sysctl.conf* + +------------------------------------------------------------------------ +USB transport (libusb) +------------------------------------------------------------------------ +The USB transport is implemented with libusb. +Libusb provides an asynchronous API for USB bulk transfers. +The transport implementation allocates a number of buffers +and submits asynchronous requests through libusb. +A single thread runs in the background +and executes the libusb event handler to process these requests. + +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +Transport parameters +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +The following parameters can be used to alter the transport's default behavior: + +* **recv_frame_size:** The size of a single receive transfers in bytes +* **num_recv_frames:** The number of simultaneous receive transfers +* **send_frame_size:** The size of a single send transfers in bytes +* **num_send_frames:** The number of simultaneous send transfers +* **concurrency_hint:** The number of threads to run the event handler diff --git a/host/docs/usrp1.rst b/host/docs/usrp1.rst index 0baa93a45..3443fd871 100644 --- a/host/docs/usrp1.rst +++ b/host/docs/usrp1.rst @@ -60,29 +60,6 @@ Example device address string representations to specify non-standard firmware a fpga=usrp1_fpga_4rx.rbf, fw=usrp1_fw_custom.ihx -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Change USB transfer parameters -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -The advanced user may manipulate parameters of the usb bulk transfers -for various reasons, such as lowering latency or increasing buffer size. -By default, the UHD will use values for these parameters -that are known to perform well on a variety of systems. -The following device address parameters can be used to manipulate USB bulk transfers: - -* **recv_xfer_size:** the size of each receive bulk transfer in bytes -* **recv_num_xfers:** the number of simultaneous receive bulk transfers -* **send_xfer_size:** the size of each send bulk transfer in bytes -* **send_num_xfers:** the number of simultaneous send bulk transfers - -Example usage, set the device address markup string to the following: -:: - - serial=12345678, recv_num_xfers=16 - - -- OR -- - - serial=12345678, recv_xfer_size=2048, recv_num_xfers=16 - ------------------------------------------------------------------------ Specifying the subdevice to use ------------------------------------------------------------------------ diff --git a/host/docs/usrp2.rst b/host/docs/usrp2.rst index 70e5ea28b..1ebab388a 100644 --- a/host/docs/usrp2.rst +++ b/host/docs/usrp2.rst @@ -166,47 +166,6 @@ The device address string representation for 2 USRP2s with IPv4 addresses 192.16 addr=192.168.10.2 192.168.20.2 ------------------------------------------------------------------------ -Resize the send and receive buffers ------------------------------------------------------------------------- -It may be useful increase the size of the socket buffers to -move the burden of buffering samples into the kernel, or to -buffer incoming samples faster than they can be processed. -However, if you application cannot process samples fast enough, -no amount of buffering can save you. - -By default, the UHD will try to resize both the send and receive buffer for optimum performance. -A warning will be printed on instantiation if the actual buffer size is insufficient. -See the OS specific notes below: - -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -OS specific notes -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -On linux, the maximum buffer sizes are capped by the sysctl values -**net.core.rmem_max** and **net.core.wmem_max**. -To change the maximum values, run the following commands: -:: - - sudo sysctl -w net.core.rmem_max=<new value> - sudo sysctl -w net.core.wmem_max=<new value> - -Set the values permanently by editing */etc/sysctl.conf* - -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -Device address params -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -To manually set the size of the buffers, -the usrp2 will accept two optional parameters in the device address. -Each parameter will accept a numeric value for the number of bytes. - -* recv_buff_size -* send_buff_size - -Example usage, set the device address markup string to the following: -:: - - addr=192.168.10.2, recv_buff_size=100e6 - ------------------------------------------------------------------------- Hardware setup notes ------------------------------------------------------------------------ |