[dpdk-dev] [PATCH v4] sched: make RED scaling configurable

[Dewar, Alan]

> > > > +int
> > > > +rte_red_set_scaling(uint16_t max_red_queue_length);
> > > > +
> > > > +/**
> > > > + * @brief Reset the RED scaling factor - only for use by RED 
> > > > +unit-tests
> > > > + *
> > > > + * @return Operation status
> > > > + */
> > > > +void
> > > > +rte_red_reset_scaling(void);
> > >
> > > As stated above, this function is probably not useful and my vote is 
> > > to
> > remove it.
> > >
> > 
> > It is needed by the revised unit-test program.  This function can't be 
> > moved into the unit-test program because it needs to reset variables 
> > that are statically declared within rte_red.c
> > 
> > 
>
> Hi Alan,
>
> We only put API that makes sense for a real app, not for unit test.

I didn't add rte_red_reset_scaling function to lib/librte_sched/rte_sched_version.map, so doesn't that mean that this function wouldn't be part of the rte_sched library's external API?
 
> About unit tests: Each test in the unit test suite should start from scratch, i.e. create a RED object from scratch, configure it, use it, free it rather than use RED objects created by previous tests. We need to avoid the latter approach, as it is creating fake dependencies between tests that alter the overall test results. Each test should be independent, and not rely on previous tests. Makes sense?

I can appreciate what you are suggesting, but rte_red.c does some one-time initialization of a module static array called rte_red_log2_1_minus_Wq.  The values assigned to elements in this array depend upon what the RED scaling factor is set to.   This means that the first RED sub-test that calls rte_red_config_init imposes its scaling factor for all subsequent RED sub-tests.    The new RED unit-tests need to use different scaling factors.

The only way to make these RED sub-tests completely independent would be to create and execute separate test images for each sub-test, rather than building all the sub-tests into a single image and using the test-harness's command-line to select which sub-test to execute. 

As an alternative I'm guessing that we could change how rte_red.c does its initialization.

Regards
Alan


>
> Regards,
> Cristian