[dpdk-dev] [PATCH v3 1/5] net/ixgbevf: set the inter-interrupt interval for EITR.

[Ferruh Yigit]

On 3/22/2018 1:01 PM, xiangxia.m.yue at gmail.com wrote:
> From: Tonghao Zhang <xiangxia.m.yue at gmail.com>
> 
> Set EITR interval as default. This patch can improve the
> performance when we enable the rx-intrrupt to process the
> packets because we hope rx-intrrupt reduce CPU. For example,
> the 200us value of EITR makes the performance better with
> the low CPU.
> 
> Users can configure the value of ITR via DPDK configuration.
> 
> The default value of ITR is 500us, compatible with RSC of ixgbe PF,
> and next patch will use the default value.
> 
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue at gmail.com>
> ---
> v1 --> v2:
> use the configure file, for different user.
> suggested by Beilei Xing, http://dpdk.org/dev/patchwork/patch/32989
> ---
>  config/common_base               |  2 ++
>  drivers/net/ixgbe/ixgbe_ethdev.c |  7 +++++++
>  drivers/net/ixgbe/ixgbe_ethdev.h | 12 ++++++++++++
>  3 files changed, 21 insertions(+)
> 
> diff --git a/config/common_base b/config/common_base
> index e74febe..2e9fded 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -196,6 +196,8 @@ CONFIG_RTE_LIBRTE_IXGBE_DEBUG_DRIVER=n
>  CONFIG_RTE_LIBRTE_IXGBE_PF_DISABLE_STRIP_CRC=n
>  CONFIG_RTE_IXGBE_INC_VECTOR=y
>  CONFIG_RTE_LIBRTE_IXGBE_BYPASS=n
> +# interval up to 1024 us
> +CONFIG_RTE_LIBRTE_IXGBE_ITR_INTERVAL=-1

I can understand this is to let user to ability to fine tune this value, the
down side is when number of these kind of tune parameters increased, it become
confusing and config options because less useful or perhaps useless.

And overall we are trying to reduce config options we have.

I can see there is already some default values in the header file, what do you
think removing the config option and go with default values defined in header?

>  
>  #
>  # Compile burst-oriented I40E PMD driver
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
> index e67389f..495e72c 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
> @@ -5780,6 +5780,13 @@ static void ixgbevf_set_vfta_all(struct rte_eth_dev *dev, bool on)
>  		if (vector_idx < base + intr_handle->nb_efd - 1)
>  			vector_idx++;
>  	}
> +
> +	/* As RX queue setting above show, all queues use the vector 0.
> +	 * Set only the ITR value of IXGBE_MISC_VEC_ID.
> +	 */
> +	IXGBE_WRITE_REG(hw, IXGBE_VTEITR(IXGBE_MISC_VEC_ID),
> +			ixgbe_calc_itr_interval(RTE_LIBRTE_IXGBE_ITR_INTERVAL)
> +			| IXGBE_EITR_CNT_WDIS);
>  }
>  
>  /**
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.h b/drivers/net/ixgbe/ixgbe_ethdev.h
> index 1db29bd..c779001 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.h
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.h
> @@ -58,6 +58,18 @@
>  		IXGBE_EITR_ITR_INT_MASK)
>  
>  
> +#define IXGBE_QUEUE_ITR_INTERVAL_MAX	1024 /* 1024us */
> +#define IXGBE_QUEUE_ITR_INTERVAL_DEFAULT	500 /* 500us */
> +
> +static inline uint16_t
> +ixgbe_calc_itr_interval(int16_t interval)
> +{
> +	if (interval < 0 || interval > IXGBE_QUEUE_ITR_INTERVAL_MAX)
> +		interval = IXGBE_QUEUE_ITR_INTERVAL_DEFAULT;
> +
> +	return IXGBE_EITR_INTERVAL_US(interval);
> +}
> +
>  /* Loopback operation modes */
>  /* 82599 specific loopback operation types */
>  #define IXGBE_LPBK_82599_NONE   0x0 /* Default value. Loopback is disabled. */
>