Re: [dpdk-dev] [PATCH v4 7/8] ethdev: support of multiple sizes of redirection table

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2014-11-06 01:02, Zhang, Helin:
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > 2014-10-31 17:03, Helin Zhang:
> > >  #define ETH_RSS_RETA_SIZE_64  64
> > >  #define ETH_RSS_RETA_SIZE_128 128
> > >  #define ETH_RSS_RETA_SIZE_512 512
> > 
> > Are these values still needed?
> 
> It was widely used in igb/ixgbe/i40e code, and app/testpmd. It is good to be kept there,
> though we can define them separately in each component. This would be more convenient
> for PMDs and user applications.

If it should be used by applications, it must stay in ethdev.

> > Why 256 is forbidden?
> 
> 256 is not a valid table size of current supported NICs, for other/future NIC which supports
> this size, it can be added later as needed.

The problem is that we don't know which value is supported for each driver.
You should add a comment like this:
/**@{
 * Some RSS RETA sizes may be not supported by some drivers.
 * Check in the PMD documentation.
 */
#define ETH_RSS_RETA_SIZE_64  64
#define ETH_RSS_RETA_SIZE_128 128
#define ETH_RSS_RETA_SIZE_512 512
/**@}*/

And then add some comments in the PMD to describe the supported sizes.

> > Maybe that some comments are needed here.
> 
> Comments might not be needed, as their names tell us what they are clearly. Did you mean
> any other annotations to be added for these macros? I am open for that to add any good
> annotations for them.

We just have to keep in mind that the API reference for users is in doxygen.
Some details are obvious for you but not clear for the user, especially if he
doesn't care about i40e.

Thanks
-- 
Thomas