Re: [dpdk-dev] [PATCH v6 0/3] DPDK ethdev callback support

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-02-23 18:30, John McNamara:
> This patchset is for a small optional addition to the ethdev library,
> to add support for callbacks at the RX and TX stages. This allows
> packet processing to be done on packets before they get returned
> to applications using rte_eth_rx_burst call.
> 
> See the RFC cover letter for the use cases:
> 
>     http://dpdk.org/ml/archives/dev/2014-December/010491.html
> 
> For this version we spent some time investigating Stephen Hemminger's
> suggestion of using the userspace RCU (read-copy-update) library for
> SMP safety:
> 
>    http://urcu.so/
> 
> The default liburcu (which defaulted to liburcu-mb) requires the least
> interaction from the end user but showed a 25% drop in packet throughput
> in the callback sample app.
> 
> The liburcu-qsbr (quiescent state) variant showed a 1% drop in packet
> throughput in the callback sample app. However it requires registered
> RCU threads in the program to periodically announce quiescent states.
> This makes it more difficult to implement for end user applications.
> 
> For this release we will document that adding and removing callbacks
> is not thread safe.
> 
> Note: Sample application documentation to follow in a patch update.
> 
> Version 6 changes:
>     * RX/TX callback functions are no longer #ifdefed out if callback
>       option is off. Instead they return ENOTSUP.
>     * Simplified callbacks #ifdefs in rte_ethdev.
> 
> Version 5 changes:
>     * Turned the callback feature on by default.
>     * Simplified #define name.
> 
> Version 4 changes:
>     * Made the callback feature a compile time option.
> 
> Version 3 changes:
>     * Removed unnecessary header file from example folder
>       (which included baremetal reference).
>     * Renamed the interrupt, RX and TX callbacks to make their function
>       clearer (using the names suggested in the mailing list comments).
>     * Squashed ABI version update into the commit it relates to.
>     * Fixed various checkpatch warnings.
> 
> Version 2 changes:
>     * Added ABI versioning.
>     * Doxygen clarifications.
> 
> Version 1 changes:
>     * Added callback removal functions.
>     * Minor fixes.
> 
> Richardson, Bruce (3):
>   ethdev: rename callbacks field to link_intr_cbs
>   ethdev: add optional rxtx callback support
>   examples: example showing use of callbacks.

Applied, thanks