linux-kernel - Re: [PATCH net 2/2] vmxnet3: use correct flag to indicate LRO feature

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Message-Id: <20180316.105406.1653568798369743500.davem@redhat.com>
Date:   Fri, 16 Mar 2018 10:54:06 -0400 (EDT)
From:   David Miller <davem@...hat.com>
To:     doshir@...are.com
Cc:     netdev@...r.kernel.org, rachel_lunnon@...rmagic.com,
        skhare@...are.com, pv-drivers@...are.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 2/2] vmxnet3: use correct flag to indicate LRO
 feature

From: Ronak Doshi <doshir@...are.com>
Date: Tue, 13 Mar 2018 12:41:41 -0700

> 'Commit 45dac1d6ea04 ("vmxnet3: Changes for vmxnet3 adapter version 2
> (fwd)")' introduced a flag "lro" in structure vmxnet3_adapter which is
> used to indicate whether LRO is enabled or not. However, the patch
> did not set the flag and hence it was never exercised.
> 
> So, when LRO is enabled, it resulted in poor TCP performance due to
> delayed acks. This issue is seen with packets which are larger than
> the mss getting a delayed ack rather than an immediate ack, thus
> resulting in high latency.
> 
> This patch removes the lro flag and directly uses device features
> against NETIF_F_LRO to check if lro is enabled.
> 
> Reported-by: Rachel Lunnon <rachel_lunnon@...rmagic.com>
> Signed-off-by: Ronak Doshi <doshir@...are.com>
> Acked-by: Shrikrishna Khare <skhare@...are.com>

Please add an appropriate "Fixes: " tag for the commit which introduced
this problem.  This helps with -stable submissions and bug fix triage.