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From: Thomas Monjalon <thomas@monjalon.net>
To: Qi Zhang <qi.z.zhang@intel.com>, Ferruh Yigit <ferruh.yigit@intel.com>
Cc: Wenzhuo Lu <wenzhuo.lu@intel.com>,
	Beilei Xing <beilei.xing@intel.com>,
	Bernard Iremonger <bernard.iremonger@intel.com>,
	dev@dpdk.org, Steve Yang <stevex.yang@intel.com>,
	Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
	Konstantin Ananyev <konstantin.ananyev@intel.com>,
	Olivier Matz <olivier.matz@6wind.com>,
	Lance Richardson <lance.richardson@broadcom.com>,
	David Marchand <david.marchand@redhat.com>
Subject: Re: [dpdk-dev] [PATCH] app/testpmd: fix MTU after device configure
Date: Mon, 16 Nov 2020 21:24:21 +0100
Message-ID: <2195073.9XJvc8EHFU@thomas> (raw)
In-Reply-To: <93c1f68a-75aa-c7f4-b245-7bd477006a07@intel.com>

16/11/2020 19:50, Ferruh Yigit:
> On 11/13/2020 11:44 AM, Ferruh Yigit wrote:
> > In 'rte_eth_dev_configure()', if 'DEV_RX_OFFLOAD_JUMBO_FRAME' is not set
> > the max frame size is limited to 'RTE_ETHER_MAX_LEN' (1518).
> > This is mistake because for the PMDs that has frame size bigger than
> > "RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN" (18 bytes), the MTU becomes
> > less than 1500, causing a valid frame with 1500 bytes payload to be
> > dropped.
> > 
> > Since 'rte_eth_dev_set_mtu()' works as expected, it is called after
> > 'rte_eth_dev_configure()' to fix the MTU.
> > It may look redundant to set MTU after 'rte_eth_dev_configure()', both
> > with default values, but it is not, the resulting MTU config can be
> > different in the device based on frame overhead of the PMD.
> > 
> > And instead of setting the MTU to default value, it is first get via
> > 'rte_eth_dev_get_mtu()' and set again, this is to cover cases MTU
> > changed from testpmd command line.
> > 
> > 'rte_eth_dev_set_mtu()', '-ENOTSUP' error is ignored to prevent
> > irrelevant warning messages for the virtual PMDs.
> > 
> > Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> > Reviewed-by: Qi Zhang <qi.z.zhang@intel.com>
> > ---
> 
> @David highlighted that 'scatter' tests are failing in the lab with this commit,
> https://lab.dpdk.org/results/dashboard/patchsets/14492/

To be more precise, this error showed up in the CI even before
the patch was merged: https://patches.dpdk.org/patch/84132/
We should be more careful with the CI results before merging.

> With above commit only 'mtu' is taken into account, so in testpmd both 
> "--max-pkt-len=N" parameter and "port config all max-pkt-len #" command are no 
> more working as expected. This seems the reason of the failure.
> 
> Technically it is possible to fix dts testcase by adding following commands:
> port stop all
> port config mtu 0 9000
> port start all
> 
> But, there may be other side affects from "max-pkt-len" is not working in 
> testpmd as expected. Reverting this one too can be safest option.

Next fix will be the right one ;)



      reply	other threads:[~2020-11-16 20:24 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-05 18:09 [dpdk-dev] [RFC] " Ferruh Yigit
2020-11-11 12:58 ` Ferruh Yigit
2020-11-13 10:37 ` Zhang, Qi Z
2020-11-13 11:44 ` [dpdk-dev] [PATCH] " Ferruh Yigit
2020-11-13 14:53   ` Andrew Rybchenko
2020-11-13 16:01     ` Ferruh Yigit
2020-11-16 18:50   ` Ferruh Yigit
2020-11-16 20:24     ` Thomas Monjalon [this message]

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