linux-kernel - Re: [PATCH net v4] atl1c: move tx cleanup processing out of interrupt

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Message-ID: <5bd5e1b9c1fdf8c9a43a0d018a005eab@mikrotik.com>
Date:   Thu, 08 Apr 2021 08:21:20 +0300
From:   Gatis Peisenieks <gatis@...rotik.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     chris.snook@...il.com, davem@...emloft.net, kuba@...nel.org,
        hkallweit1@...il.com, jesse.brandeburg@...el.com,
        dchickles@...vell.com, tully@...rotik.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v4] atl1c: move tx cleanup processing out of interrupt

On 2021-04-07 19:55, Eric Dumazet wrote:
> 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.

Thank you Eric, for heads up, the v5 patch sent for net-next in response 
to
David Miller comment already does that.