Re: [dpdk-dev] [BUG] ixgbe vector cannot compile without bulk alloc

["Liang, Cunming" <cunming.liang@intel.com>]

> -----Original Message-----
> From: Richardson, Bruce
> Sent: Thursday, January 29, 2015 8:38 PM
> To: Liang, Cunming
> Cc: Thomas Monjalon; dev@dpdk.org
> Subject: Re: [dpdk-dev] [BUG] ixgbe vector cannot compile without bulk alloc
> 
> On Thu, Jan 29, 2015 at 11:39:37PM +0000, Liang, Cunming wrote:
> >
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> > > Sent: Thursday, January 29, 2015 4:28 PM
> > > To: Thomas Monjalon
> > > Cc: dev@dpdk.org
> > > Subject: Re: [dpdk-dev] [BUG] ixgbe vector cannot compile without bulk alloc
> > >
> > > On Thu, Jan 29, 2015 at 11:18:01PM +0100, Thomas Monjalon wrote:
> > > > 2014-12-01 18:22, Thomas Monjalon:
> > > > > 2014-12-01 17:18, Bruce Richardson:
> > > > > > On Mon, Dec 01, 2014 at 06:10:18PM +0100, Thomas Monjalon wrote:
> > > > > > > These 2 configuration options are incompatible:
> > > > > > > 	CONFIG_RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC=n
> > > > > > > 	CONFIG_RTE_IXGBE_INC_VECTOR=y
> > > > > > > Building this config gives this error:
> > > > > > > 	lib/librte_pmd_ixgbe/ixgbe_rxtx_vec.c:69:24:
> > > > > > > 	error: ‘struct igb_rx_queue’ has no member named
> ‘fake_mbuf’
> > > > > > >
> > > > > > > I'd like a confirmation that it will be always incompatible.
> > > > > > > Thanks
> > > > > >
> > > > > > Hi Thomas,
> > > > > >
> > > > > > I don't think these options should always be incompatible, though as
> you
> > > point
> > > > > > out you do need to turn on bulk alloc support in order to use the vector
> > > PMD.
> > > > > > Why do you ask? There are no immediate plans to remove the
> dependency
> > > on our end.
> > > >
> > > > So you confirm that the ixgbe vpmd really needs Rx bulk alloc and this kind
> of
> > > > patch cannot work at all (I don't know the design of vpmd):
> > > >
> > > > --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> > > > +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.c
> > > > @@ -2119,12 +2119,12 @@ ixgbe_reset_rx_queue(struct igb_rx_queue
> *rxq)
> > > >                 rxq->rx_ring[i] = zeroed_desc;
> > > >         }
> > > >
> > > > -#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
> > > >         /*
> > > >          * initialize extra software ring entries. Space for these extra
> > > >          * entries is always allocated
> > > >          */
> > > >         memset(&rxq->fake_mbuf, 0x0, sizeof(rxq->fake_mbuf));
> > > > +#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
> > > >         for (i = 0; i < RTE_PMD_IXGBE_RX_MAX_BURST; ++i) {
> > > >                 rxq->sw_ring[rxq->nb_rx_desc + i].mbuf =
> > > &rxq->fake_mbuf;
> > > >         }
> > > > --- a/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> > > > +++ b/lib/librte_pmd_ixgbe/ixgbe_rxtx.h
> > > > @@ -127,9 +127,9 @@ struct igb_rx_queue {
> > > >         uint8_t             crc_len;  /**< 0 if CRC stripped, 4
> otherwise.
> > > */
> > > >         uint8_t             drop_en;  /**< If not 0, set
> SRRCTL.Drop_En.
> > > */
> > > >         uint8_t             rx_deferred_start; /**< not in global dev
> start.
> > > */
> > > > -#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
> > > >         /** need to alloc dummy mbuf, for wraparound when scanning
> hw
> > > ring */
> > > >         struct rte_mbuf fake_mbuf;
> > > > +#ifdef RTE_LIBRTE_IXGBE_RX_ALLOW_BULK_ALLOC
> > > >         /** hold packets to return to application */
> > > >         struct rte_mbuf *rx_stage[RTE_PMD_IXGBE_RX_MAX_BURST*2];
> > > >  #endif
> > > >
> > > > > I think the compilation shouldn't fail without a proper message.
> > > > > In order to distinguish a real compilation error from an incompatibility,
> > > > > we should add a warning in the makefile.
> > > > > Ideally, the build system should handle dependencies. But waiting this
> ideal
> > > > > time, a warning would be graceful.
> > > >
> > > > Do you agree that something like this would be OK?
> > > >
> > > > --- a/lib/librte_pmd_ixgbe/Makefile
> > > > +++ b/lib/librte_pmd_ixgbe/Makefile
> > > > @@ -114,4 +114,8 @@ DEPDIRS-$(CONFIG_RTE_LIBRTE_IXGBE_PMD) +=
> > > lib/librte_eal lib/librte_ether
> > > >  DEPDIRS-$(CONFIG_RTE_LIBRTE_IXGBE_PMD) += lib/librte_mempool
> > > lib/librte_mbuf
> > > >  DEPDIRS-$(CONFIG_RTE_LIBRTE_IXGBE_PMD) += lib/librte_net
> > > lib/librte_malloc
> > > >
> > > > +ifeq
> > >
> ($(CONFIG_RTE_IXGBE_INC_VECTOR)$(CONFIG_RTE_LIBRTE_IXGBE_RX_ALLOW_B
> > > ULK_ALLOC),yn)
> > > > +$(error The ixgbe vpmd depends on Rx bulk alloc)
> > > > +endif
> > > > +
> > > >  include $(RTE_SDK)/mk/rte.lib.mk
> > > >
> > >
> > > Something like the above looks like a good solution to me.
> > >
> > > /Bruce
> > [Liang, Cunming] To avoid compile complain, this one is ok.
> > It's doable to remove the dependence between two.
> > We can submit it in a separate patch.
> > >
> Sure, if that can be done, it sounds good. I don't see a huge problem with
> having a dependency between the two - I can't really see a use case for someone
> wanting the vector driver but to have the bulk-alloc scalar one disabled.
> So, I'm easy either way, with just flagging the warning or removing the
> dependency completely.
> 
> Follow-on question - can we look to remove the bulk alloc switch completely.
> The user can force the selection of the RX function and TX functions at run time
> via the nic setup parameters, so I don't see the need to limit the choices at
> compile time - other than the vpmd which obviously has an instruction set
> dependency.
[Liang, Cunming] Agree.
> 
> /Bruce