From: Bruce Richardson <bruce.richardson@intel.com>
To: Wenzhuo Lu <wenzhuo.lu@intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] doc: more clarification for i40e 16 bytes desc
Date: Tue, 31 Oct 2017 10:04:00 +0000 [thread overview]
Message-ID: <20171031100400.GA10572@bricha3-MOBL3.ger.corp.intel.com> (raw)
In-Reply-To: <1509421233-81295-1-git-send-email-wenzhuo.lu@intel.com>
On Tue, Oct 31, 2017 at 11:40:33AM +0800, Wenzhuo Lu wrote:
> The description of i40e 16 bytes descriptor is not clear
> enough. Add more details.
>
> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
Thanks for the clarification, it's better now. Couple of minor tweaks I
would suggest below.
Otherwise:
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
> doc/guides/nics/i40e.rst | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> index a0946e6..771620c 100644
> --- a/doc/guides/nics/i40e.rst
> +++ b/doc/guides/nics/i40e.rst
> @@ -398,13 +398,24 @@ used to classify MPLS packet by using a command in testpmd like:
> testpmd> ethertype_filter 0 add mac_ignr 00:00:00:00:00:00 ethertype \
> 0x8847 fwd queue <M>
>
> -16 Byte Descriptor cannot be used on DPDK VF
> -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +16 Bytes Descriptor setting on DPDK VF
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We tend to refer to these as "16-byte" and "32-byte" descriptors in the
singular, not "16-bytes".
>
> +Currently the VF's RX descriptor mode is decided by PF. There's no PF-VF
> +interface for VF to request the RX descriptor mode, also no interface to nofify
> +VF its own RX descriptor mode.
> +Until i40e 2.1.26, the Linux i40e driver doesn't support 16 bytes RX descriptor.
This implies that the 2.1.26 driver does support setting the descriptor
size, though later text implies that this is not the case.
Therefore, I suggest changing "Until i40e 2.1.26", to "For all available
versions of the i40e driver," and omit the version number, since it will
soon be out of date otherwise. The only time we should need to update
this is when/if there is a kernel version that does support reporting or
seting the descriptor size.
> If the Linux i40e kernel driver is used as host driver, while DPDK i40e PMD
> -is used as the VF driver, DPDK cannot choose 16 byte receive descriptor. That
> -is to say, user should keep ``CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n`` in
> -config file.
> +is used as the VF driver, DPDK cannot choose 16 byte receive descriptor. The
> +reason is that the RX descriptor is already set to 32 bytes by the i40e kernel
> +driver. That is to say, user should keep
> +``CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n`` in config file.
> +In the future, if the Linux i40e driver supports 16 bytes RX descriptor, user
> +should make sure the DPDK VF uses the same RX descriptor mode, 16 bytes or 32
> +bytes, as the PF driver.
> +
> +The same rule for DPDK PF + DPDK VF. The PF and VF should use the same RX
> +descriptor mode. Or the VF RX will not work.
>
> Receive packets with Ethertype 0x88A8
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> --
> 1.9.3
>
next prev parent reply other threads:[~2017-10-31 10:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-25 2:54 [dpdk-dev] [PATCH] " Wenzhuo Lu
2017-10-25 8:36 ` Bruce Richardson
2017-10-31 1:53 ` Lu, Wenzhuo
2017-10-31 3:40 ` [dpdk-dev] [PATCH v2] " Wenzhuo Lu
2017-10-31 10:04 ` Bruce Richardson [this message]
2017-11-01 2:03 ` Lu, Wenzhuo
2017-11-01 2:45 ` [dpdk-dev] [PATCH v3] doc: more clarification for i40e 16 byte desc Wenzhuo Lu
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