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From: Ferruh Yigit <ferruh.yigit@intel.com>
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
Date: Fri, 9 Mar 2018 15:03:42 +0000	[thread overview]
Message-ID: <eba6d4ec-dd2e-c4ad-de6d-ae82510cd74a@intel.com> (raw)
In-Reply-To: <20180308024702.25974-4-johndale@cisco.com>

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

> 
> 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>

<...>

  reply	other threads:[~2018-03-09 15:03 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 [this message]
2018-03-09 15:51             ` Ananyev, Konstantin
2018-03-09 15:57               ` Ferruh Yigit
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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