Re: [dpdk-dev] [PATCH v5 0/2] app/testpmd: improve multiprocess support

["Pattan, Reshma" <reshma.pattan@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Marcin Kerlin
> Sent: Friday, September 30, 2016 3:01 PM
> To: dev@dpdk.org
> Cc: De Lara Guarch, Pablo <pablo.de.lara.guarch@intel.com>;
> thomas.monjalon@6wind.com; Kerlin, MarcinX <marcinx.kerlin@intel.com>
> Subject: [dpdk-dev] [PATCH v5 0/2] app/testpmd: improve multiprocess support
> 
> This patch ensure not overwrite device data in the multiprocess application.
> 
> 1)Changes in the library introduces continuity in array rte_eth_dev_data[] shared
> between all processes. Secondary process adds new entries in free space instead
> of overwriting existing entries.
> 
> 2)Changes in application testpmd allow secondary process to attach the
> mempool created by primary process rather than create new and in the case of
> quit or force quit to free devices data from shared array rte_eth_dev_data[].
> 
> -------------------------
> How to reproduce the bug:
> 
> 1) Run primary process:
> ./testpmd -c 0xf -n 4 --socket-mem='512,0' -w 03:00.1 -w 03:00.0 --proc-
> type=primary --file-prefix=xz1 -- -i
> 
> (gdb) print rte_eth_devices[0].data.name
> $52 = "3:0.1"
> (gdb) print rte_eth_devices[1].data.name
> $53 = "3:0.0"
> 
> 2) Run secondary process:
> ./testpmd -c 0xf0 --socket-mem='512,0' -n 4 -v -b 03:00.1 -b 03:00.0 --vdev
> 'eth_pcap0,rx_pcap=/var/log/device1.pcap, tx_pcap=/var/log/device2.pcap'
> --proc-type=secondary --file-prefix=xz1 -- -i
> 
> (gdb) print rte_eth_devices[0].data.name
> $52 = "eth_pcap0"
> (gdb) print rte_eth_devices[1].data.name
> $53 = "eth_pcap1"
> 
> 3) Go back to the primary and re-check:
> (gdb) print rte_eth_devices[0].data.name
> $54 = "eth_pcap0"
> (gdb) print rte_eth_devices[1].data.name
> $55 = "eth_pcap1"
> 
> It means that secondary process overwrite data of primary process.
> 
> This patch fix it and now if we go back to the primary and re-check then
> everything is fine:
> (gdb) print rte_eth_devices[0].data.name
> $56 = "3:0.1"
> (gdb) print rte_eth_devices[1].data.name
> $57 = "3:0.0"
> 
> So after this fix structure rte_eth_dev_data[] will keep all data one after the
> other instead of overwriting:
> (gdb) print rte_eth_dev_data[0].name
> $52 = "3:0.1"
> (gdb) print rte_eth_dev_data[1].name
> $53 = "3:0.0"
> (gdb) print rte_eth_dev_data[2].name
> $54 = "eth_pcap0"
> (gdb) print rte_eth_dev_data[3].name
> $55 = "eth_pcap1"
> and so on will be append in the next indexes
> 
> If secondary process will be turned off then also will be deleted from array:
> (gdb) print rte_eth_dev_data[0].name
> $52 = "3:0.1"
> (gdb) print rte_eth_dev_data[1].name
> $53 = "3:0.0"
> (gdb) print rte_eth_dev_data[2].name
> $54 = ""
> (gdb) print rte_eth_dev_data[3].name
> $55 = ""
> this also allows re-use index 2 and 3 for next another process
> -------------------------
> 
> Breaking ABI:
> Changes in the library librte_ether causes extending existing structure
> rte_eth_dev_data with a new field lock. The reason is that this structure is
> sharing between all the processes so it should be protected against attempting
> to write from two different processes.
> 
> Tomasz Kulasek sent announce ABI change in librte_ether on 21 July 2016.
> I would like to join to this breaking ABI, if it is possible.
> 
> v2:
> * fix syntax error in version script
> v3:
> * changed scope of function
> * improved description
> v4:
> * fix syntax error in version script
> v5:
> * fix header file
> 
> Marcin Kerlin (2):
>   librte_ether: add protection against overwrite device data
>   app/testpmd: improve handling of multiprocess
> 
>  app/test-pmd/testpmd.c                 | 37 +++++++++++++-
>  app/test-pmd/testpmd.h                 |  1 +
>  lib/librte_ether/rte_ethdev.c          | 90 +++++++++++++++++++++++++++++++---
>  lib/librte_ether/rte_ethdev.h          | 12 +++++
>  lib/librte_ether/rte_ether_version.map |  6 +++
>  5 files changed, 136 insertions(+), 10 deletions(-)
> 
> --
> 1.9.1

Acked-by: Reshma Pattan <reshma.pattan@intel.com>