[ovs-dev] [RFC 2/2] dpdk: Update INSTALL.DPDK.md to reflect new config

[Zoltan Kiss]

On 04/12/15 16:15, Gray, Mark D wrote:
>>   5. Start vswitchd:
>> >
>> >-   DPDK configuration arguments can be passed to vswitchd via `--dpdk`
>> >-   argument. This needs to be first argument passed to vswitchd process.
>> >-   dpdk arg -c is ignored by ovs-dpdk, but it is a required parameter
>> >-   for dpdk initialization.
>> >-
>> >+   DPDK configuration arguments can be passed to vswitchd via the
>> >Open_vSwitch
>> >+   other_config database. The recognized configuration options are listed.
>> >+
>> >+   * dpdk
>> >+   This is a boolean configuration option. A value of 'true' tells
>> >+   Open_vSwitch to initialize the DPDK EAL. A set of nominal defaults are
>> >+   provided so that simply enabling this option will be sufficient to configure
>> >+   DPDK enabled ports.
>> >+   * dpdk_core_mask
>> >+   This is DPDK's -c command line option, and specifies the core mask to
>> >+   the EAL.
> Why exactly do we need this again? We have "other_config:pmd-cpu-mask" which
> should set the affinity of the pmd threads. The affinities of the other standard pthreads
> should by a system administrator. Or, if the intention is that this would allow us
> to set affinities for the other threads, then the name should be changed to something
> more meaningful.
>

My understanding is that OVS-DPDK doesn't really use any "lcore"'s from 
DPDK, but rather creates its own threads, and set the lcore_id in 
pmd_thread_setaffinity_cpu(). At least, I haven't seen any 
rte_eal_[mp_]remote_launch() call in the code, so I think the -c option 
should only have 1 core set for the master thread, everything else just 
waste memory.