Re: [dpdk-dev] [PATCH 1/6] ether: enhancement for VMDQ support

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

2014-10-15 09:47, Chen, Jing D:
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > 2014-10-15 06:59, Chen, Jing D:
> > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > > >  enum rte_eth_rx_mq_mode {
> > > > > -	ETH_MQ_RX_NONE = 0,  /**< None of DCB,RSS or VMDQ mode */
> > > > > -
> > > > > -	ETH_MQ_RX_RSS,       /**< For RX side, only RSS is on */
> > > > > -	ETH_MQ_RX_DCB,       /**< For RX side,only DCB is on. */
> > > > > -	ETH_MQ_RX_DCB_RSS,   /**< Both DCB and RSS enable */
> > > > > -
> > > > > -	ETH_MQ_RX_VMDQ_ONLY, /**< Only VMDQ, no RSS nor DCB */
> > > > > -	ETH_MQ_RX_VMDQ_RSS,  /**< RSS mode with VMDQ */
> > > > > -	ETH_MQ_RX_VMDQ_DCB,  /**< Use VMDQ+DCB to route traffic to queues */
> > > > > -	ETH_MQ_RX_VMDQ_DCB_RSS, /**< Enable both VMDQ and DCB in VMDq */
> > > > > +	/**< None of DCB,RSS or VMDQ mode */
> > > > > +	ETH_MQ_RX_NONE = 0,
> > > > > +
> > > > > +	/**< For RX side, only RSS is on */
> > > > > +	ETH_MQ_RX_RSS = ETH_MQ_RX_RSS_FLAG,
> > > > > +	/**< For RX side,only DCB is on. */
> > > > > +	ETH_MQ_RX_DCB = ETH_MQ_RX_DCB_FLAG,
> > > > > +	/**< Both DCB and RSS enable */
> > > > > +	ETH_MQ_RX_DCB_RSS = ETH_MQ_RX_RSS_FLAG | ETH_MQ_RX_DCB_FLAG,
> > > > > +
> > > > > +	/**< Only VMDQ, no RSS nor DCB */
> > > > > +	ETH_MQ_RX_VMDQ_ONLY = ETH_MQ_RX_VMDQ_FLAG,
> > > > > +	/**< RSS mode with VMDQ */
> > > > > +	ETH_MQ_RX_VMDQ_RSS = ETH_MQ_RX_RSS_FLAG | ETH_MQ_RX_VMDQ_FLAG,
> > > > > +	/**< Use VMDQ+DCB to route traffic to queues */
> > > > > +	ETH_MQ_RX_VMDQ_DCB = ETH_MQ_RX_VMDQ_FLAG | ETH_MQ_RX_DCB_FLAG,
> > > > > +	/**< Enable both VMDQ and DCB in VMDq */
> > > > > +	ETH_MQ_RX_VMDQ_DCB_RSS = ETH_MQ_RX_RSS_FLAG | ETH_MQ_RX_DCB_FLAG |
> > > > > +				 ETH_MQ_RX_VMDQ_FLAG,
> > > > >  };
> > > >
> > > > Why not simply remove all these combinations and keep only flags?
> > > > Please keep it simple.
> > >
> > > One reason is back-compatibility.
> > 
> > I understand but I think we should prefer cleanup.
> > As there is no way to advertise deprecation of flags, it should be
> > simply removed.
> > 
> > > Another reason is not all NIC driver support all the combined modes, only
> > > limited sets
> > > driver supported. Under this condition, it's better to use the combination
> > > definition
> > > (VMDQ_DCB, DCB_RSS, etc) to let driver check whether it supports.
> > 
> > Driver can do the same checks with simple flags and it's probably simpler
> > (e.g. a driver which doesn't support VMDQ had no need to check all VMDQ
> > combinations).
[...]
> case ETH_MQ_RX_VMDQ_FLAG |  ETH_MQ_RX_DCB_FLAG:
[...] 
> Won't it look weird for reading? In fact, it's more complex in
> rte_eth_dev_check_mq_mode(),
> With the change, the code will look weird.

I think that defining all combinations of flags is more weird.

> In fact, I don't see benefit with the change to old code. New PMD driver
> can use simple flag while old driver (IXGBE/IGB) can use original definition.

If nobody else agree with my point of view, I'll accept yours.

-- 
Thomas