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From: Thomas Monjalon <thomas@monjalon.net>
To: andrew.rybchenko@oktetlabs.ru, ferruh.yigit@intel.com
Cc: dev@dpdk.org, getelson@nvidia.com, dev@dpdk.org,
	matan@nvidia.com, Ori Kam <orika@nvidia.com>
Subject: Re: [dpdk-dev] [PATCH v2] doc: flow rule removal on port stop
Date: Tue, 24 Nov 2020 12:04:51 +0100
Message-ID: <3388506.zBEybLLHgT@thomas> (raw)
In-Reply-To: <2076472.bjLukMjepe@thomas>

There is also a testpmd patch pending about this behaviour:
	https://patches.dpdk.org/patch/75353/

22/11/2020 17:55, Thomas Monjalon:
> Andrew, any comment on this v2?
> (disclosure: I did not read it)
> 
> 
> 18/11/2020 17:15, Gregory Etelson:
> > 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 | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> > index ea203e0ca4..4cff9332fa 100644
> > --- a/doc/guides/prog_guide/rte_flow.rst
> > +++ b/doc/guides/prog_guide/rte_flow.rst
> > @@ -3229,10 +3229,12 @@ Caveats
> >    temporarily replacing the burst function pointers), an appropriate error
> >    code must be returned (``EBUSY``).
> >  
> > -- PMDs, not applications, 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.
> > +- Applications, not PMDs, are responsible for maintaining flow rules
> > +  configuration when closing, stopping or restarting a port or performing other
> > +  actions which may affect them.
> > +  Applications must assume that after port close, stop or restart all flows
> > +  related to that port are not valid, hardware rules are destroyed and relevant
> > +  PMD resources are released.
> >  
> >  For devices exposing multiple ports sharing global settings affected by flow
> >  rules:





  reply	other threads:[~2020-11-24 11:05 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-16 11:18 [dpdk-dev] [PATCH] " 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
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 [this message]
2020-11-24 14:41   ` Ajit Khaparde
2020-11-25 23:33     ` Thomas Monjalon

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