diff mbox series

[1/5] ethdev: add capability to keep flow rules on restart

Message ID 20211005005216.2427489-2-dkozlyuk@nvidia.com (mailing list archive)
State Superseded, archived
Delegated to: Ferruh Yigit
Headers
Series Flow entites behavior on port restart |

Checks

Context Check Description
ci/checkpatch success coding style OK

Commit Message

Dmitry Kozlyuk Oct. 5, 2021, 12:52 a.m. UTC 
  From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>

Currently, it is not specified what happens to the flow rules when
the device is stopped, possibly reconfigured, then started.
If flow rules were kept, it could be convenient for application
developers, because they wouldn't need to save and restore them.
However, due to the number of flows and possible creation rate it is
impractical to save all flow rules in DPDK layer. This means that flow
rules persistence really depends on whether PMD and HW can implement it
efficiently. It is proposed for PMDs to advertise this capability
if supported using a new flag.

If the device is being reconfigured in a way that is incompatible with
existing flow rules, PMD is required to report an error.
This is mandatory, because flow API does not supply users with
capabilities, so this is the only way for a user to learn that
configuration is invalid. For example, if queue count changes and the
action of a flow rule specifies queues that are going away, the user
must update or remove the flow rule before removing the queues.

Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
---
 doc/guides/prog_guide/rte_flow.rst | 9 +++++++++
 lib/ethdev/rte_ethdev.h            | 2 ++
 2 files changed, 11 insertions(+)

Comments

Ori Kam Oct. 6, 2021, 6:15 a.m. UTC | #1 
Hi Dmitry,

> -----Original Message-----
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Sent: Tuesday, October 5, 2021 3:52 AM
> Subject: [PATCH 1/5] ethdev: add capability to keep flow rules on restart
> 
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> 
> Currently, it is not specified what happens to the flow rules when the device is
> stopped, possibly reconfigured, then started.
> If flow rules were kept, it could be convenient for application developers,
> because they wouldn't need to save and restore them.
> However, due to the number of flows and possible creation rate it is
> impractical to save all flow rules in DPDK layer. This means that flow rules
> persistence really depends on whether PMD and HW can implement it
> efficiently. It is proposed for PMDs to advertise this capability if supported
> using a new flag.
> 
> If the device is being reconfigured in a way that is incompatible with existing
> flow rules, PMD is required to report an error.
> This is mandatory, because flow API does not supply users with capabilities, so
> this is the only way for a user to learn that configuration is invalid. For
> example, if queue count changes and the action of a flow rule specifies queues
> that are going away, the user must update or remove the flow rule before
> removing the queues.
> 
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> ---

Acked-by: Ori Kam <orika@nvidia.com>
Thanks,
Ori
Somnath Kotur Oct. 6, 2021, 6:55 a.m. UTC | #2 
On Wed, Oct 6, 2021 at 11:45 AM Ori Kam <orika@nvidia.com> wrote:
>
> Hi Dmitry,
>
> > -----Original Message-----
> > From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> > Sent: Tuesday, October 5, 2021 3:52 AM
> > Subject: [PATCH 1/5] ethdev: add capability to keep flow rules on restart
> >
> > From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> >
> > Currently, it is not specified what happens to the flow rules when the device is
> > stopped, possibly reconfigured, then started.
> > If flow rules were kept, it could be convenient for application developers,
> > because they wouldn't need to save and restore them.
> > However, due to the number of flows and possible creation rate it is
> > impractical to save all flow rules in DPDK layer. This means that flow rules
> > persistence really depends on whether PMD and HW can implement it
> > efficiently. It is proposed for PMDs to advertise this capability if supported
> > using a new flag.
> >
> > If the device is being reconfigured in a way that is incompatible with existing
> > flow rules, PMD is required to report an error.
> > This is mandatory, because flow API does not supply users with capabilities, so
> > this is the only way for a user to learn that configuration is invalid. For
> > example, if queue count changes and the action of a flow rule specifies queues
> > that are going away, the user must update or remove the flow rule before
> > removing the queues.
> >
> > Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> > ---
>
> Acked-by: Ori Kam <orika@nvidia.com>
> Thanks,
> Ori
Acked-by: Somnath Kotur <somnath.kotur@broadcom.com>
Ajit Khaparde Oct. 6, 2021, 5:15 p.m. UTC | #3 
On Mon, Oct 4, 2021 at 5:52 PM <dkozlyuk@oss.nvidia.com> wrote:
>
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
>
> Currently, it is not specified what happens to the flow rules when
> the device is stopped, possibly reconfigured, then started.
> If flow rules were kept, it could be convenient for application
> developers, because they wouldn't need to save and restore them.
> However, due to the number of flows and possible creation rate it is
> impractical to save all flow rules in DPDK layer. This means that flow
> rules persistence really depends on whether PMD and HW can implement it
> efficiently. It is proposed for PMDs to advertise this capability
> if supported using a new flag.
>
> If the device is being reconfigured in a way that is incompatible with
> existing flow rules, PMD is required to report an error.
> This is mandatory, because flow API does not supply users with
> capabilities, so this is the only way for a user to learn that
> configuration is invalid. For example, if queue count changes and the
> action of a flow rule specifies queues that are going away, the user
> must update or remove the flow rule before removing the queues.
>
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>

Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
diff mbox series

Patch

diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
index 2b42d5ec8c..0a03097a7c 100644
--- a/doc/guides/prog_guide/rte_flow.rst
+++ b/doc/guides/prog_guide/rte_flow.rst
@@ -87,6 +87,15 @@  To avoid resource leaks on the PMD side, handles must be explicitly
 destroyed by the application before releasing associated resources such as
 queues and ports.
 
+By default flow rules are implicitly destroyed when the device is stopped.
+If the device advertises ``RTE_DEV_CAPA_FLOW_RULE_KEEP``, flow rules persist
+across device stop and start with possible reconfiguration in between.
+Some configuration changes may be incompatible with existing flow rules,
+in this case ``rte_eth_dev_configure()`` or ``rte_eth_rx/tx_queue_setup()``
+will fail. At this point PMD developers are encouraged to log errors identical
+to the ones that would be emitted by ``rte_flow_create()`` if the new
+configuration was active.
+
 The following sections cover:
 
 - **Attributes** (represented by ``struct rte_flow_attr``): properties of a
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index afdc53b674..d24de5e8fa 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -1478,6 +1478,8 @@  struct rte_eth_conf {
 #define RTE_ETH_DEV_CAPA_RUNTIME_RX_QUEUE_SETUP 0x00000001
 /** Device supports Tx queue setup after device started. */
 #define RTE_ETH_DEV_CAPA_RUNTIME_TX_QUEUE_SETUP 0x00000002
+/** Device keeps flow rules across restart and reconfiguration. */
+#define RTE_ETH_DEV_CAPA_FLOW_RULE_KEEP 0x00000004
 /**@}*/
 
 /*