Hi Olivier, >Hi Keith, > >On 03/21/2016 06:38 PM, Wiles, Keith wrote: >>> On Mar 21, 2016, at 11:10 AM, Olivier Matz <olivier.matz at 6wind.com> >>> wrote: >>> >>> When using RSS, the number of rxqs has to be a power of two. >>> This is a problem because there is no API is dpdk that makes >>> the application aware of that. >>> >>> A good compromise is to allow the application to request a >>> number of rxqs that is not a power of 2, but having inactive >>> queues that will never receive packets. In this configuration, >>> a warning will be issued to users to let them know that >>> this is not an optimal configuration. >> >> Not sure I like this solution. I think an error should be returned with a >> log message instead. What if the next driver needs power of three or must be >> odd or even number. >> >> The bigger problem is the application is no longer portable for any given >> nic configuration. >> >> We need a method for the application to query the system for these types of >> information. But as we do not have that API we need to just error the >> request off. > > >The initial problem is that the driver says "I support a maximum >of X queues" and if the application configures a lower number, it >gets an error. > >There is no API in DPDK to tell that only specific number of queues >are supported. Adding an API is a solution, but in this case it's >probably overkill. With this patch, the driver can present the proper >number of queues to the application, knowing that the spreading of >the packets won't be ideal (some queues won't receive packets), but >it will work. > >A step further in this direction would be to configure more queues >than asked in hardware to do a better spreading, almost similar to >what is done with RETA tables in mlx5. But this is more complicated >to do, especially if we want it for 16.04.
Well I guess I must agree with the solution, but I am not real happy. Can we mark this a temp fix until we figure out a cleaner solution as I would not want this type of solution forever or be the standard way to handle these problems. > >Hope this is clearer with the explanation. > >Regards, >Olivier > > Regards, Keith
