Re: [dpdk-dev] [PATCH] i40e: enable i40e pmd on ARM platform

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Jianbo,

> > Hi, Jianbo
> >
> > I have tested you patch on my X86 platform,  the single core performance for Non-vector PMD will have about 1Mpps drop
> > Non-vector PMD single core performance with patch               :  ~33.9 Mpps
> > Non-vector PMD single core performance without patch        :  ~35.1 Mpps
> > Is there any way to avoid such performance drop on X86? Thanks.
> >
> 
> I think we can place a compiling condition before rte_rmb() to avoid performance decrease on x86.
> For example:  #if defined(RTE_ARCH_ARM) || defined(RTE_ARCH_ARM64)

I suppose you can use rte_smp_rmb() here?
Konstantin

> 
> Thanks!
> Jianbo
> 
> > BRs
> > Lei
> >
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jianbo Liu
> > Sent: Tuesday, August 2, 2016 2:58 PM
> > To: dev@dpdk.org; Zhang, Helin <helin.zhang@intel.com>; Wu, Jingjing
> > <jingjing.wu@intel.com>
> > Cc: Jianbo Liu <jianbo.liu@linaro.org>
> > Subject: [dpdk-dev] [PATCH] i40e: enable i40e pmd on ARM platform
> >
> > And add read memory barrier to avoid status inconsistency between two RX descriptors readings.
> >
> > Signed-off-by: Jianbo Liu <jianbo.liu@linaro.org>
> > ---
> >  config/defconfig_arm64-armv8a-linuxapp-gcc | 2 +-
> >  doc/guides/nics/overview.rst               | 2 +-
> >  drivers/net/i40e/i40e_rxtx.c               | 2 ++
> >  3 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/config/defconfig_arm64-armv8a-linuxapp-gcc
> > b/config/defconfig_arm64-armv8a-linuxapp-gcc
> > index 1a17126..08f282b 100644
> > --- a/config/defconfig_arm64-armv8a-linuxapp-gcc
> > +++ b/config/defconfig_arm64-armv8a-linuxapp-gcc
> > @@ -46,6 +46,6 @@ CONFIG_RTE_EAL_IGB_UIO=n
> >
> >  CONFIG_RTE_LIBRTE_IVSHMEM=n
> >  CONFIG_RTE_LIBRTE_FM10K_PMD=n
> > -CONFIG_RTE_LIBRTE_I40E_PMD=n
> > +CONFIG_RTE_LIBRTE_I40E_INC_VECTOR=n
> >
> >  CONFIG_RTE_SCHED_VECTOR=n
> > diff --git a/doc/guides/nics/overview.rst
> > b/doc/guides/nics/overview.rst index 6abbae6..5175591 100644
> > --- a/doc/guides/nics/overview.rst
> > +++ b/doc/guides/nics/overview.rst
> > @@ -138,7 +138,7 @@ Most of these differences are summarized below.
> >     Linux VFIO                     Y Y   Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y                     Y   Y Y
> >     Other kdrv                                                         Y Y               Y
> >     ARMv7                                                                        Y             Y Y
> > -   ARMv8                                              Y Y Y Y                   Y         Y   Y Y
> > +   ARMv8                                  Y           Y Y Y Y                   Y         Y   Y Y
> >     Power8                                                             Y Y       Y
> >     TILE-Gx                                                                      Y
> >     x86-32                         Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y       Y           Y Y Y
> > diff --git a/drivers/net/i40e/i40e_rxtx.c
> > b/drivers/net/i40e/i40e_rxtx.c index 554d167..4004b8e 100644
> > --- a/drivers/net/i40e/i40e_rxtx.c
> > +++ b/drivers/net/i40e/i40e_rxtx.c
> > @@ -994,6 +994,8 @@ i40e_rx_scan_hw_ring(struct i40e_rx_queue *rxq)
> >                                         I40E_RXD_QW1_STATUS_SHIFT;
> >                 }
> >
> > +               rte_rmb();
> > +
> >                 /* Compute how many status bits were set */
> >                 for (j = 0, nb_dd = 0; j < I40E_LOOK_AHEAD; j++)
> >                         nb_dd += s[j] & (1 <<
> > I40E_RX_DESC_STATUS_DD_SHIFT);
> > --
> > 2.4.11
> >