Re: [PATCH v6 00/22] introduce fail-safe PMD

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 7/7/2017 1:09 AM, Gaetan Rivet wrote:
> This PMD intercepts and manages Ethernet device removal events issued by
> slave PMDs and re-initializes them transparently when brought back so that
> existing applications do not need to be modified to benefit from true
> hot-plugging support.
> 
> The stacked PMD approach shares many similarities with the bonding PMD but
> with a different purpose. While bonding provides the ability to group
> several links into a single logical device for enhanced throughput and
> supports fail-over at link level, this one manages the sudden disappearance
> of the underlying device; it guarantees applications face a valid device in
> working order at all times.
> 
> Each fail-safe instance is configured to run atop one or several
> devices, with one defined as the preferred device. Hot-plug events are
> handled on all of them, and Tx is always directed to the preferred device
> if present or to the next available failover device (Rx is always performed
> on all devices for simplicity).
> 
> Moreover, the configured slaves (preferred or failover) do not need to be
> present at initialization time and may appear later.
> 
> Slaves configuration is continuously synchronized with that of the virtual
> device, which exposes their common set of capabilities to the application.
> Failure to apply the current configuration state to a slave for any reason
> simply reschedules its initialization.
> 
> This patchset depends on:
> 
> eal: complete attach / detach support
> http://dpdk.org/ml/archives/dev/2017-May/066366.html
> http://dpdk.org/dev/patchwork/patch/24522/
> 
> ethdev: add flow API rule copy function
> http://dpdk.org/ml/archives/dev/2017-May/066145.html
> http://dpdk.org/dev/patchwork/patch/24406/
> 
> ethdev: add isolated mode to flow API
> http://dpdk.org/ml/archives/dev/2017-April/064327.html
> http://dpdk.org/dev/patchwork/patch/23741/
> 
> v1 --> v2:
> 
>   - Wrote documentation
>   - Fixed commit logs, signed-off-by
>   - Added LSC event support
>   - A few minor fixes
> 
> v2 --> v3:
> 
>   - Numerous bug fixes.
>   - Complete sub-EAL rework to follow new bus API.
>   - burst protection on sub removal.
>   - more flexible sub definition.
>   - flow isolated mode support.
> 
> v3 --> v4:
> 
>   - Split back commits
>        net/failsafe: add fast burst functions
>        net/failsafe: support device removal
>     That were squashed by error during a rebase
>   - Fix segfault on port plugin
>   - Fix isolate mode support for MLX4 ports plugin
> 
> v4 --> v5:
> 
>   - Follow new plug / unplug API.
> 
> v5 --> v6:
> 
>   - Follow new hotplug API.
>   - Improve usability of hotplug API.
>   - Fix rte_dev hotplug API implementation.
>   - Introduce rte_eal_devargs_rmv API as EXPERIMENTAL.
>   - Use it to clean up resources on hotplug_remove.
>   - Fix hotplug implementation and support un pci bus.
>     The scan was not idempotent, nor clean.
>     Neither were the device fields.
>   - Implement plug operation for vdev bus.
>     This is needed for hotplug support and to make the EAL
>     independent from vdev-specific API.
>   - Remove useless parameters from plug / unplug API.
> 
> This patchset is fairly big and complex. The hotplug API has been rushed and
> has never been tested outside of the special case of vdev bus.
> 
> These evolutions are proposed alongside this PMD as only this PMD allows to test
> this API at the moment, and without those evolutions this PMD cannot be used.
> 
> Gaetan Rivet (22):
>   eal: return device handle upon plugin
>   eal: fix hotplug add
>   devargs: introduce removal function
>   eal: release devargs on device removal
>   pci: use given name as generic name
>   pci: fix generic driver pointer on probe error
>   pci: fix hotplug operations
>   vdev: add dev to vdev macro
>   vdev: implement plug operation
>   bus: remove useless plug parameter
>   ethdev: save VLAN filter setting
>   ethdev: add deferred intermediate device state
>   ethdev: count devices consistently
>   net/failsafe: add fail-safe PMD
>   net/failsafe: add plug-in support
>   net/failsafe: add flexible device definition
>   net/failsafe: support flow API
>   net/failsafe: support offload capabilities
>   net/failsafe: add fast burst functions
>   net/failsafe: support device removal
>   net/failsafe: support link status change event
>   net/failsafe: support flow API isolation mode

Hi Gaetan,

The failsafe PMD postponed to RC2, to mainly let eal level dependencies
be resolved first, and I believe it is OK to get a PMD in RC2 because
its scope is limited.

But in this new version of the patchset, there are many patches touches
to eal and ethdev level. I don't think it is good idea to get these
changes in RC2 and with next-net tree.

I believe these should be resolved in main repo, in RC1. And failsafe as
a PMD, can go in RC2 via next-net.

What do you think separating eal and ethdev bits of the patchset and
target RC1?

Thanks,
ferruh