[dpdk-dev] [PATCH RFC 0/3] DPDK ethdev callback support
Qiu, Michael
michael.qiu at intel.com
Wed Dec 24 06:06:40 CET 2014
Hi Bruce,
I haven't seen the third patch of you patch set.
Just want to know if only me missed.
Thanks,
Michael
On 12/23/2014 12:48 AM, Bruce Richardson wrote:
> This RFC is for a small addition to the ethdev library, to add in 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.
>
> Use case: the first use case for this is to enable a consistent set of
> packets mbufs to be received by applications irrespective of the NIC used
> to receive those. For example, for a port type that does not support RSS,
> a callback on RX can be configured to calculate a hash in software.
> Similarly, this mechanism can be used to add other information to mbufs
> as they are received, such as timestamps or sequence numbers, without cluttering
> up the main packet processing path with checks for whether packets have these
> fields filled in or not.
> A second use case is ease of intrumenting existing code. The example application
> shows how combining a timestamp insertion callback on RX can be paired with a
> latency calculation callback on TX to easily instrument any application for
> packet latency.
> A third use case is to potentially extend existing NIC capabilities beyond
> what is currently supported. For example, where flow director capabilities
> can match up to a certain limit of flows - in the thousands, in the case of
> NICs using the ixgbe driver - a callback can extend this to potentially
> millions of flows by using a software hash table lookup inline for packets
> that missing the hardware lookup filters. It would all appear transparent
> to the packet handling code in the main application.
>
> Future extensions: in future the ethdev library can be extended to provide
> a standard set of callbacks for use by drivers.
>
> For now this patch set is RFC and still needs additional work for creating
> a remove function for callbacks and to add in additional testing code.
> Since this adds in new code into the critical data path, I have run some
> performance tests using testpmd with the ixgbe vector drivers (i.e. the
> fastest, fast-path we have :-) ). Performance drops due to this patch
> seems minimal to non-existant, rough tests on my system indicate a drop
> of perhaps 1%.
>
> All feedback welcome.
>
> Bruce Richardson (3):
> ethdev: rename callbacks field to intr_cbs
> ethdev: Add in data rxtx callback support
> examples: example showing use of callbacks.
>
> app/test/virtual_pmd.c | 2 +-
> examples/rxtx_callbacks/Makefile | 57 +++++++++
> examples/rxtx_callbacks/basicfwd.c | 222 +++++++++++++++++++++++++++++++++
> examples/rxtx_callbacks/basicfwd.h | 46 +++++++
> lib/librte_ether/rte_ethdev.c | 103 +++++++++++++--
> lib/librte_ether/rte_ethdev.h | 125 ++++++++++++++++++-
> lib/librte_pmd_bond/rte_eth_bond_api.c | 2 +-
> 7 files changed, 543 insertions(+), 14 deletions(-)
> create mode 100644 examples/rxtx_callbacks/Makefile
> create mode 100644 examples/rxtx_callbacks/basicfwd.c
> create mode 100644 examples/rxtx_callbacks/basicfwd.h
>
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