Re: [dpdk-dev] [PATCH 2/5] ethdev: add capability to keep shared objects on restart

[Ori Kam <orika@nvidia.com>]

Hi Dmitry,

> -----Original Message-----
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> Sent: Tuesday, October 5, 2021 3:52 AM
> To: dev@dpdk.org
> Cc: Dmitry Kozlyuk <dkozlyuk@nvidia.com>; Ori Kam <orika@nvidia.com>;
> NBU-Contact-Thomas Monjalon <thomas@monjalon.net>; Ferruh Yigit
> <ferruh.yigit@intel.com>; Andrew Rybchenko
> <andrew.rybchenko@oktetlabs.ru>
> Subject: [PATCH 2/5] ethdev: add capability to keep shared objects on restart
> 
> From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> 
> rte_flow_action_handle_create() did not mention what happens with an
> indirect action when a device is stopped, possibly reconfigured, and started
> again. It is natural for some indirect actions to be persistent, like counters and
> meters; keeping others just saves application time and complexity. However,
> not all PMDs can support it.
> It is proposed to add a device capability to indicate if indirect actions are kept
> across the above sequence or implicitly destroyed.
> 
> In the future, indirect actions may not be the only type of objects shared
> between flow rules. The capability bit intends to cover all possible types of such
> objects, hence its name.
> 
> It may happen that in the future a PMD acquires support for a type of shared
> objects that it cannot keep across a restart. It is undesirable to stop advertising
> the capability so that applications that don't use objects of the problematic type
> can still take advantage of it.
> This is why PMDs are allowed to keep only a subset of shared objects provided
> that the vendor mandatorily documents it.
> 
> If the device is being reconfigured in a way that is incompatible with an existing
> shared objects, 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 RSS indirect action specifies queues that
> are going away, the user must update the action before removing the queues
> or remove the action and all flow rules that were using it.
> 
> Signed-off-by: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
> ---

Acked-by: Ori Kam <orika@nvidia.com>
Thanks,
Ori