netdev - Re: [PATCH net 00/15] netpoll: avoid capture effects for NAPI drivers

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Message-ID: <ACD08072-B5A0-4A5D-8E02-30E5F763124D@fb.com>
Date:   Mon, 24 Sep 2018 21:18:13 +0000
From:   Song Liu <songliubraving@...com>
To:     Eric Dumazet <edumazet@...gle.com>
CC:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Michael Chan <michael.chan@...adcom.com>,
        Ariel Elior <ariel.elior@...ium.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>
Subject: Re: [PATCH net 00/15] netpoll: avoid capture effects for NAPI drivers



> On Sep 24, 2018, at 2:05 PM, Eric Dumazet <edumazet@...gle.com> wrote:
> 
>> 
>> Interesting, maybe a bnxt specific issue.
>> 
>> It seems their model is to process TX/RX notification in the same queue,
>> they throw away RX events if budget == 0
>> 
>> It means commit e7b9569102995ebc26821789628eef45bd9840d8 is wrong and
>> must be reverted.
>> 
>> Otherwise, we have a possibility of blocking a queue under netpoll pressure.
> 
> Hmm, actually a revert might not be enough, since code at lines 2030-2031
> would fire and we might not call napi_complete_done() anyway.
> 
> Unfortunately this driver logic is quite complex.
> 
> Could you test on other NIC eventually ?
> 

It actually runs OK on ixgbe. 

@Michael, could you please help us with this? 

Thanks,
Song