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 <getel...@nvidia.com> > Acked-by: Ori Kam <or...@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: >
