From: Thomas Monjalon <thomas@monjalon.net>
To: dev@dpdk.org
Cc: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Subject: [dpdk-dev] [PATCH v3] doc: add timestamp upper limitation in mlx5 guide
Date: Wed, 5 Aug 2020 17:26:10 +0200 [thread overview]
Message-ID: <20200805152610.277087-1-thomas@monjalon.net> (raw)
In-Reply-To: <1595865064-12892-1-git-send-email-viacheslavo@mellanox.com>
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
next prev parent reply other threads:[~2020-08-05 15:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 15:51 [dpdk-dev] [PATCH v2] doc/mlx5: add timestamp upper limitation description Viacheslav Ovsiienko
2020-08-05 15:26 ` Thomas Monjalon [this message]
2020-08-05 15:43 ` [dpdk-dev] [PATCH v3] doc: add timestamp upper limitation in mlx5 guide Thomas Monjalon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200805152610.277087-1-thomas@monjalon.net \
--to=thomas@monjalon.net \
--cc=dev@dpdk.org \
--cc=viacheslavo@mellanox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).