From: Viacheslav Ovsiienko <viachesl...@mellanox.com> Add description about Tx scheduling timestamp upper limit. If timestamp exceed the value, it is marked by PMD as being into "too-distant-future" and not scheduled at all (is being sent without any wait).
Signed-off-by: Viacheslav Ovsiienko <viachesl...@mellanox.com> Signed-off-by: Thomas Monjalon <tho...@monjalon.net> --- v2: typo fix v3: more typos fixed and small rewording --- doc/guides/nics/mlx5.rst | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst index 90202c0bbb..211c0c5a6c 100644 --- a/doc/guides/nics/mlx5.rst +++ b/doc/guides/nics/mlx5.rst @@ -253,6 +253,14 @@ Limitations reported via device xstats to assist applications to detect the time-related problems. + The timestamp upper "too-distant-future" limit + at the moment of invoking the Tx burst routine + can be estimated as ``tx_pp`` option (in nanoseconds) multiplied by 2^23. + Please note, for the testpmd txonly mode, + the limit is deduced from the expression:: + + (n_tx_descriptors / burst_size + 1) * inter_burst_gap + There is no any packet reordering according timestamps is supposed, neither within packet burst, nor between packets, it is an entirely application responsibility to generate packets and its timestamps -- 2.27.0
