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Subject: Re: [PATCH net v4] atl1c: move tx cleanup processing out of interrupt
To:     Gatis Peisenieks <gatis@mikrotik.com>, chris.snook@gmail.com,
        davem@davemloft.net, kuba@kernel.org, hkallweit1@gmail.com,
        jesse.brandeburg@intel.com, dchickles@marvell.com,
        tully@mikrotik.com, eric.dumazet@gmail.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <c8327d4bb516dd4741878c64fa6485cd@mikrotik.com>
From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <7c5dad3e-950d-8ec9-8b9d-bbce41fafaa4@gmail.com>
Date:   Wed, 7 Apr 2021 18:55:47 +0200
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On 4/6/21 4:49 PM, Gatis Peisenieks wrote:
> Tx queue cleanup happens in interrupt handler on same core as rx queue
> processing. Both can take considerable amount of processing in high
> packet-per-second scenarios.
> 
> Sending big amounts of packets can stall the rx processing which is unfair
> and also can lead to out-of-memory condition since __dev_kfree_skb_irq
> queues the skbs for later kfree in softirq which is not allowed to happen
> with heavy load in interrupt handler.
> 

[ ... ]

> diff --git a/net/core/dev.c b/net/core/dev.c
> index 0f72ff5d34ba..489ac60b530c 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -6789,6 +6789,7 @@ int dev_set_threaded(struct net_device *dev, bool threaded)
> 
>      return err;
>  }
> +EXPORT_SYMBOL(dev_set_threaded);
> 
>  void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
>              int (*poll)(struct napi_struct *, int), int weight)

This has already been done in net-next

Please base your patch on top of net-next, this can not be backported to old
versions anyway, without some amount of pain.