On Thu, Oct 13, 2016 at 02:35:05PM +, Oleg Kuporosov wrote:
>
> Hello DPDK Developers,
>
> Financial Services Industry which is pretty eager for several DPDK
> features especially low latency while high throughput. The major issue
> so far for increasing DPDK adoption there is requirement for several
> applications (capturers, some trading algorithms) to support of accurate
> timestamping. The requirement mostly came from regulatory and customers
> need strictly follow it.
>
> Current state of timestamping support in DPDK looks pretty good:
> - there is API to enable/disable timestamping acquisition by
>rte_eth_timesync_enable/disable
> - get timestamps itself by timesync_read_rx/tx_timestamp
> - and even implementation of NTP IEEE 1588 for time synchronization
>by rte_eth_timesync_adjust_read/write_time APIs.
>
> But it misses the most important feature there ? embedding timestamp
> in rte_mbuf aligning it with packet.
>
> We would like to change this to increase DPDK adoption for several new
> DPDK-based applications for FSI segment. It also might be very
> applicable for several RT media and debugging purposes of network
> flows/streams in other segments like HPC.
>
> There are several thoughts how to improve there:
> - include uint64_t timestamp field into rte_mbuf with minimal impact
>to throughput/latency. Keep it just simple uint64_t in ns (more than
>580 years) would be enough for immediate needs while using full
>struct timespec with twice bigger size would have much stronger
>performance impact as missed cacheline0. It is possible as there is
>6-bytes gap in 1st cacheline (fast path) and moving uint16_t
>vlan_tci_outer field to 2nd cacheline.
> - such move will only impact for pretty rare usable VLAN RX stripping
>mode for outer TCI (it used only for one NIC i40e from the whole
>set and keep minimal performance impact for timestamps.
> - PMD can fill the field in their callback completion routines
>depending on enabling this feature in runtime.
>
> We evaluated other possible options but looks it will have even worse
> performance impact.
>
>
> Oleg Kuporosov (3):
> mbuf: embedding timestamp into the packet
> app/testpmd: enabled control for packet timestamps
> net/mlx5: implementation of Rx packet timestamping support
>
> app/test-pmd/cmdline.c | 122 +++
> app/test-pmd/parameters.c | 4 +
> app/test-pmd/testpmd.c | 5 +
> app/test-pmd/testpmd.h | 1 +
> doc/guides/testpmd_app_ug/run_app.rst | 4 +
> doc/guides/testpmd_app_ug/testpmd_funcs.rst | 7 +
> drivers/net/mlx5/mlx5.c | 7 +-
> drivers/net/mlx5/mlx5.h | 10 +-
> drivers/net/mlx5/mlx5_defs.h| 4 +
> drivers/net/mlx5/mlx5_ethdev.c | 222
> +++-
> drivers/net/mlx5/mlx5_rxq.c | 2 +
> drivers/net/mlx5/mlx5_rxtx.c| 19 ++-
> drivers/net/mlx5/mlx5_rxtx.h| 7 +-
> drivers/net/mlx5/mlx5_time.h| 53 +++
> drivers/net/mlx5/mlx5_trigger.c | 1 +
> lib/librte_eal/common/include/rte_time.h| 45 ++
> lib/librte_mbuf/rte_mbuf.h | 6 +-
> 17 files changed, 507 insertions(+), 12 deletions(-)
> create mode 100644 drivers/net/mlx5/mlx5_time.h
>
> Thanks,
> Oleg.
> --
> 1.8.3.1
Reviewed-by: Nelio Laranjeiro
--
N?lio Laranjeiro
6WIND