From: Ferruh Yigit <ferruh.yigit@intel.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
John Daley <johndale@cisco.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, Hyong Youb Kim <hyonkim@cisco.com>
Subject: Re: [dpdk-dev] [PATCH v3 03/10] net/enic: heed the requested max Rx packet size
Date: Fri, 9 Mar 2018 15:57:46 +0000 [thread overview]
Message-ID: <a0e1b56a-6476-580b-efcd-44741582e3fc@intel.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB97725890F22461@irsmsx105.ger.corp.intel.com>
On 3/9/2018 3:51 PM, Ananyev, Konstantin wrote:
>
> Hi everyone,
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ferruh Yigit
>> Sent: Friday, March 9, 2018 3:04 PM
>> To: John Daley <johndale@cisco.com>
>> Cc: dev@dpdk.org; Hyong Youb Kim <hyonkim@cisco.com>
>> Subject: Re: [dpdk-dev] [PATCH v3 03/10] net/enic: heed the requested max Rx packet size
>>
>> On 3/8/2018 2:46 AM, John Daley wrote:
>>> From: Hyong Youb Kim <hyonkim@cisco.com>
>>>
>>> Currently, enic completely ignores the requested max Rx packet size
>>> (rxmode.max_rx_pkt_len). The desired behavior is that the NIC hardware
>>> drops packets larger than the requested size, even though they are
>>> still smaller than MTU.
>>
>> Your description looks reasonable but is there reason of two levels of limits,
>> max_rx_pkt_len and MTU, why not just use MTU. There is already a mail thread to
>> clarify max_rx_pkt_len [1].
>>
>> Is this work based on an application that uses max_rx_pkt_len and to make PMD
>> compatible with that application? If so we can continue with patch, but if the
>> patch is to implement DPDK properly I suggest postponing this until
>> max_rx_pkt_len clarified.
>>
>> [1]
>> https://dpdk.org/ml/archives/dev/2018-March/092178.html
>
> I think there are quite a lot apps these days that might rely on setting MTU via
> rxmode.max_rx_pkt_len.
> I think we need to support them till we (ever) deprecate rxmode.max_rx_pkt_len.
Right. I was trying to save effort in case something changes related
max_rx_pkt_len, but since it is not clear yet, will continue with this patch.
> Konstantin
>
>>
>>>
>>> Cisco VIC does not have such a feature. But, we can accomplish a
>>> similar (not same) effect by reducing the size of posted receive
>>> buffers. Packets larger than the posted size get truncated, and the
>>> receive handler drops them. This is also how the kernel enic driver
>>> enforces the Rx side MTU.
>>>
>>> This workaround works only when scatter mode is *not* used. When
>>> scatter is used, there is currently no way to support
>>> rxmode.max_rx_pkt_len, as the NIC always receives packets up to MTU.
>>>
>>> For posterity, add a copious amount of comments regarding the
>>> hardware's drop/receive behavior with respect to max/current MTU.
>>>
>>> Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
>>> Reviewed-by: John Daley <johndale@cisco.com>
>>
>> <...>
>
next prev parent reply other threads:[~2018-03-09 15:57 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-24 19:17 [dpdk-dev] [PATCH] net/enic: remove 'extern' in .h file function declarations John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: allow the user to change RSS settings John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: heed the requested max Rx packet size John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: remove the VLAN filter handler John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: add Rx/Tx queue configuration getters John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: allocate stats DMA buffer upfront during probe John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: support Rx queue interrupts John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] doc: describe Rx bytes counter behavior for enic John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: use memcpy to avoid strict aliasing warnings John Daley
2018-02-24 19:17 ` [dpdk-dev] [PATCH] net/enic: support for meson John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 00/10] enic patchset John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 01/10] net/enic: remove 'extern' in .h file function declarations John Daley
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 00/10] enic PMD patchset John Daley
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 01/10] net/enic: remove 'extern' in .h file function declarations John Daley
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 02/10] net/enic: allow the user to change RSS settings John Daley
2018-03-09 14:35 ` Ferruh Yigit
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 03/10] net/enic: heed the requested max Rx packet size John Daley
2018-03-09 15:03 ` Ferruh Yigit
2018-03-09 15:51 ` Ananyev, Konstantin
2018-03-09 15:57 ` Ferruh Yigit [this message]
2018-03-10 0:37 ` Hyong Youb Kim
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 04/10] net/enic: remove the VLAN filter handler John Daley
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 05/10] net/enic: add Rx/Tx queue configuration getters John Daley
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 06/10] net/enic: allocate stats DMA buffer upfront during probe John Daley
2018-03-08 2:46 ` [dpdk-dev] [PATCH v3 07/10] net/enic: support Rx queue interrupts John Daley
2018-03-08 2:47 ` [dpdk-dev] [PATCH v3 08/10] doc: describe Rx bytes counter behavior for enic John Daley
2018-03-08 22:14 ` Stephen Hemminger
2018-03-09 0:52 ` Hyong Youb Kim
2018-03-09 1:48 ` Stephen Hemminger
2018-03-08 2:47 ` [dpdk-dev] [PATCH v3 09/10] net/enic: use memcpy to avoid strict aliasing warnings John Daley
2018-03-08 2:47 ` [dpdk-dev] [PATCH v3 10/10] net/enic: support for meson John Daley
2018-03-08 9:49 ` Bruce Richardson
2018-03-09 16:00 ` [dpdk-dev] [PATCH v3 00/10] enic PMD patchset Ferruh Yigit
2018-03-10 0:49 ` Hyong Youb Kim
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 02/10] net/enic: allow the user to change RSS settings John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 03/10] net/enic: heed the requested max Rx packet size John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 04/10] net/enic: remove the VLAN filter handler John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 05/10] net/enic: add Rx/Tx queue configuration getters John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 06/10] net/enic: allocate stats DMA buffer upfront during probe John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 07/10] net/enic: support Rx queue interrupts John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 08/10] doc: describe Rx bytes counter behavior for enic John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 09/10] net/enic: use memcpy to avoid strict aliasing warnings John Daley
2018-03-06 1:46 ` [dpdk-dev] [PATCH v2 10/10] net/enic: support for meson John Daley
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