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author | Sascha Hauer <s.hauer@pengutronix.de> | 2022-09-14 15:53:02 +0200 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2022-09-14 15:53:02 +0200 |
commit | 6beb3f8f91f12f5fdf037b171e81ccd595017b59 (patch) | |
tree | 57dd93f3dcb641ec1d7c955cbf51725a22dbcefc /Documentation | |
parent | 55f13b3f6a25d85a3469e74bdd3dc26fe20e7909 (diff) | |
parent | 7deef7aec1425288ccabd61d6e383c74684815dd (diff) | |
download | barebox-6beb3f8f91f12f5fdf037b171e81ccd595017b59.tar.gz barebox-6beb3f8f91f12f5fdf037b171e81ccd595017b59.tar.xz |
Merge branch 'for-next/tftp'
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/filesystems/tftp.rst | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/Documentation/filesystems/tftp.rst b/Documentation/filesystems/tftp.rst index a292765e25..e88ad3dd4c 100644 --- a/Documentation/filesystems/tftp.rst +++ b/Documentation/filesystems/tftp.rst @@ -20,3 +20,43 @@ Example: In addition to the TFTP filesystem implementation, barebox does also have a :ref:`tftp command <command_tftp>`. + +RFC 7440 "windowsize" support +============================= + +barebox supports the tftp windowsize option for downloading files. It +is not implemented for uploads. + +Generally, this option greatly improves the download speed (factors +4-30 are not uncommon). But choosing a too large windowsize can have +the opposite effect. Performance depends on: + + - the network infrastructure: when the tftp server sends files with + 1Gb/s but there are components in the network (switches or the + target nic) which support only 100 Mb/s, packets will be dropped. + + The lower the internal buffers of the bottleneck components, the + lower the optimal window size. + + In practice (iMX8MP on a Netgear GS108Ev3 with a port configured to + 100 Mb/s) it had to be reduced to + + .. code-block:: console + + global tftp.windowsize=26 + + for example. + + - the target network driver: datagrams from server will arive faster + than they can be processed and must be buffered internally. For + example, the `fec-imx` driver reserves place for + + .. code-block:: c + + #define FEC_RBD_NUM 64 + + packets before they are dropped + + - partially the workload: copying downloaded files to ram will be + faster than burning them into flash. Latter can consume internal + buffers quicker so that windowsize might be reduced |