RE: [PATCH v2] sched: enable CMAN at runtime

["Danilewicz, MarcinX" <marcinx.danilewicz@intel.com>]

+this time to dpdk.org , to test removal of automatic footer

Hi Cristian,

< snip >

> > +++ b/lib/sched/rte_sched.h
> > @@ -128,6 +128,8 @@ extern "C" {
> >  enum rte_sched_cman_mode {
> >  	RTE_SCHED_CMAN_RED, /**< Random Early Detection (RED) */
> >  	RTE_SCHED_CMAN_PIE, /**< Proportional Integral Controller
< snip >
> Can you please explain why you need to add the new
> RTE_SCHED_CMAN_NONE value to this enumeration and what is the ABI
> breakage that you are trying to avoid?
> 
well, it was third value for cases when no RED or PIE is configured from config file

Initially I have found this error:
          1 data member change:
            type of 'rte_sched_cman_params* rte_sched_subport_params::cman_params' changed:
              in pointed to type 'struct rte_sched_cman_params' at rte_sched.h:166:1:
                type size hasn't changed
                1 data member change:
                  type of 'rte_sched_cman_mode rte_sched_cman_params::cman_mode' changed:
                    type size hasn't changed
                    1 enumerator insertion:
                      'rte_sched_cman_mode::RTE_SCHED_CMAN_NONE' value '0'
                    2 enumerator changes:
                      'rte_sched_cman_mode::RTE_SCHED_CMAN_RED' from value '0' to '1' at rte_sched.h:128:1
                      'rte_sched_cman_mode::RTE_SCHED_CMAN_PIE' from value '1' to '2' at rte_sched.h:128:1

Error: ABI issue reported for 'abidiff --suppr devtools/libabigail.abignore --no-added-syms 
--headers-dir1 reference/usr/local/include --headers-dir2 install/usr/local/include reference
/dump/librte_sched.dump install/dump/librte_sched.dump'
ABIDIFF_ABI_CHANGE, this change requires a review (abidiff flagged this as a potential issue).

Then I moved RTE_SCHED_CMAN_NONE to the end of existing enum, as advices. That removed error above.

In that moment, I needed quick fix for discussion about change for showing approach. Not final fix.


< snip >

> The library expects the struct rte_sched_subport_params:: cman_params to
> be NULL when the CMAN is disabled, why is this not enough to detect that
> CMAN is disabled? I suggest to keep the current approach.
Ok, I'll try to use NULL instead.

Kind Regards,
/Marcin