DPDK patches and discussions
 help / color / mirror / Atom feed
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
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

  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:

* 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 \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ https://inbox.dpdk.org/dev \
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git