DPDK patches and discussions
 help / color / mirror / Atom feed
From: Gregory Etelson <getelson@nvidia.com>
To: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"john.mcnamara@intel.com" <john.mcnamara@intel.com>,
	"marko.kovacevic@intel.com" <marko.kovacevic@intel.com>,
	Matan Azrad <matan@nvidia.com>, Ori Kam <orika@nvidia.com>,
	NBU-Contact-Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [dpdk-dev] [PATCH] doc: flow rule removal on port stop
Date: Wed, 18 Nov 2020 09:06:23 +0000
Message-ID: <MN2PR12MB4639F44503090F49B7E57449A5E10@MN2PR12MB4639.namprd12.prod.outlook.com> (raw)
In-Reply-To: <017d57a9-70f3-eeef-e43f-9c981e6535aa@oktetlabs.ru>

> >> On 11/17/20 10:18 PM, Gregory Etelson wrote:
> >>> There is a discrepancy between RTE ETHDEV API and flow rules guide
> >>> regarding flow rules maintenance after port stop.  RTE ETHDEV API in
> >>> librte_ethdev.h declares that flow rules will not be stored in PMD
> >>> after port stop:
> >>>   >>>>> Quite start
> >>>   Please note that some configuration is not stored between calls to
> >>>   rte_eth_dev_stop()/rte_eth_dev_start(). The following configuration
> >>>   will be retained:
> >>>
> >>>   - MTU
> >>>   - flow control settings
> >>>   - receive mode configuration (promiscuous mode, all-multicast mode,
> >>>     hardware checksum mode, RSS/VMDQ settings etc.)
> >>>   - VLAN filtering configuration
> >>>   - default MAC address
> >>>   - MAC addresses supplied to MAC address array
> >>>   - flow director filtering mode (but not filtering rules)
> >>>   - NIC queue statistics mappings
> >>>   <<<< Quote end
> >>>
> >>> PMD cannot always correctly restore flow rules after port stop /
> >>> port start because application may alter port configuration after
> >>> port stop without PMD knowledge about undergoing changes.  Consider
> >>> the following scenario:
> >>> application configures 2 queues 0 and 1 and creates a flow rule with
> >>> 'queue index 1' action. After that application stops the port and
> >>> removes queue 1.
> >>> Although PMD can implement flow rule shadow copy to be used for
> >>> restore after port start, attempt to restore flow rule from shadow
> >>> will fail in example above and PMD could not notify application
> >>> about that failure.  As the result, flow rules map in HW will differ
> >>> from what application expects.  In addition, flow rules shadow copy
> >>> used for port start restore consumes considerable amount of system
> >>> memory, especially in systems with millions of flow rules.
> >>>
> >>> Signed-off-by: Gregory Etelson <getelson@nvidia.com>
> >>> Acked-by: Ori Kam <orika@nvidia.com>
> >>> ---
> >>>   doc/guides/prog_guide/rte_flow.rst | 5 ++---
> >>>   1 file changed, 2 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/doc/guides/prog_guide/rte_flow.rst
> >>> b/doc/guides/prog_guide/rte_flow.rst
> >>> index 944e8242d6..dfe5a40f8e 100644
> >>> --- a/doc/guides/prog_guide/rte_flow.rst
> >>> +++ b/doc/guides/prog_guide/rte_flow.rst
> >>> @@ -3055,10 +3055,9 @@ Caveats
> >>>     temporarily replacing the burst function pointers), an
> >>> appropriate
> >> error
> >>>     code must be returned (``EBUSY``).
> >>>
> >>> -- PMDs, not applications, are responsible for maintaining flow
> >>> rules
> >>> +- Applications, not PMDs, are responsible for maintaining flow
> >>> +rules
> >>>     configuration when stopping and restarting a port or performing
> >>> other
> >>> -  actions which may affect them. They can only be destroyed
> >>> explicitly by
> >>> -  applications.
> >>> +  actions which may affect them.
> >>>
> >>>   For devices exposing multiple ports sharing global settings
> >>> affected
> >> by flow
> >>>   rules:
> >>>
> >>
> >> Re-reading it, it still looks vague. What happens on:
> >>   - port stop without removal of flow rule before
> >>   - port close without removal of flow rules before
> >>   - port reset (which could be stop/start, e.g. to recover from error
> >> condition)
> >
> > PMD should remove all flows related to hardware resource that was
> invalidated.
> 
> Stop? Close? I agree and documentation should say so in a bit clear way.

I'll post updated document patch.

  reply	other threads:[~2020-11-18  9:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-16 11:18 Gregory Etelson
2020-11-17 19:18 ` Gregory Etelson
2020-11-17 19:56   ` Andrew Rybchenko
2020-11-18  8:59     ` Gregory Etelson
2020-11-18  9:04       ` Andrew Rybchenko
2020-11-18  9:06         ` Gregory Etelson [this message]
2020-11-18 16:15 ` [dpdk-dev] [PATCH v2] " Gregory Etelson
2020-11-22 16:55   ` Thomas Monjalon
2020-11-24 11:04     ` Thomas Monjalon
2020-11-24 14:41   ` Ajit Khaparde
2020-11-25 23:33     ` 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=MN2PR12MB4639F44503090F49B7E57449A5E10@MN2PR12MB4639.namprd12.prod.outlook.com \
    --to=getelson@nvidia.com \
    --cc=andrew.rybchenko@oktetlabs.ru \
    --cc=dev@dpdk.org \
    --cc=john.mcnamara@intel.com \
    --cc=marko.kovacevic@intel.com \
    --cc=matan@nvidia.com \
    --cc=orika@nvidia.com \
    --cc=thomas@monjalon.net \
    /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

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 \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


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