linux-kernel - Re: [PATCH] veth: ignore peer tx_dropped when counting local rx

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Message-Id: <20200305.173413.1141876751815244581.davem@davemloft.net>
Date:   Thu, 05 Mar 2020 17:34:13 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     jianglidong@...il.com
Cc:     ast@...nel.org, daniel@...earbox.net, hawk@...nel.org,
        john.fastabend@...il.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, jianglidong3@...com
Subject: Re: [PATCH] veth: ignore peer tx_dropped when counting local
 rx_dropped

From: Lidong Jiang <jianglidong@...il.com>
Date: Wed,  4 Mar 2020 09:49:29 +0800

> From: Jiang Lidong <jianglidong3@...com>
> 
> When local NET_RX backlog is full due to traffic overrun,
> peer veth tx_dropped counter increases. At that time, list
> local veth stats, rx_dropped has double value of peer
> tx_dropped, even bigger than transmit packets by peer.
> 
> In NET_RX softirq process, if any packet drop case happens,
> it increases dev's rx_dropped counter and returns NET_RX_DROP.
> 
> At veth tx side, it records any error returned from peer netif_rx
> into local dev tx_dropped counter.
> 
> In veth get stats process, it puts local dev rx_dropped and
> peer dev tx_dropped into together as local rx_drpped value.
> So that it shows double value of real dropped packets number in
> this case.
> 
> This patch ignores peer tx_dropped when counting local rx_dropped,
> since peer tx_dropped is duplicated to local rx_dropped at most cases.
> 
> Signed-off-by: Jiang Lidong <jianglidong3@...com>

This makes sense to me, applied, thank you.