Add description about Tx scheduling timstamp upper limit. It timstamp 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 <viacheslavo@mellanox.com> --- v1->v2: typo fix doc/guides/nics/mlx5.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst index 90202c0..b9bd3db 100644 --- a/doc/guides/nics/mlx5.rst +++ b/doc/guides/nics/mlx5.rst @@ -253,6 +253,13 @@ 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`` devarog (in nanoseconds) + multiplied by 2^23. Please note, for the testpmd txonly testcase 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 -- 1.8.3.1
From: Viacheslav Ovsiienko <viacheslavo@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 <viacheslavo@mellanox.com> Signed-off-by: Thomas Monjalon <thomas@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
05/08/2020 17:26, Thomas Monjalon:
> From: Viacheslav Ovsiienko <viacheslavo@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 <viacheslavo@mellanox.com>
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---
> v2: typo fix
> v3: more typos fixed and small rewording
Applied