Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller

From	David Miller <davem@davemloft.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller
Date	2015-11-11 17:30 +0100
Message-ID	<qtGry-592-59@gated-at.bofh.it> (permalink)
References	<qtrLQ-3YD-19@gated-at.bofh.it> <qttaV-4YI-1@gated-at.bofh.it> <qtCHh-2HY-23@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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From: Måns Rullgård <mans@mansr.com>
Date: Wed, 11 Nov 2015 12:22:28 +0000

> David Miller <davem@davemloft.net> writes:
> 
>> From: Måns Rullgård <mans@mansr.com>
>> Date: Wed, 11 Nov 2015 00:40:09 +0000
>>
>>> When the DMA complete interrupt arrives, the next chain should be
>>> kicked off as quickly as possible, and I don't see why that would
>>> benefit from being done in napi context.
>>
>> NAPI isn't about low latency, it's about fairness and interrupt
>> mitigation.
>>
>> You probably don't even realize that all of the TX SKB freeing you do
>> in the hardware interrupt handler end up being actually processed by a
>> scheduled software interrupt anyways.
>>
>> So you are gaining almost nothing by not doing TX completion in NAPI
>> context, whereas by doing so you would be gaining a lot including
>> more simplified locking or even the ability to do no locking at all.
> 
> TX completion is separate from restarting the DMA, and moving that to
> NAPI may well be a good idea.  Should I simply napi_schedule() if the
> hardware indicates TX is complete and do the cleanup in the NAPI poll
> function?

... just like every other high end driver... Yes.
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Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller Francois Romieu <romieu@fr.zoreil.com> - 2015-11-11 00:40 +0100
  Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 01:50 +0100
    Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 03:20 +0100
      Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 13:30 +0100
        Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 14:10 +0100
          Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller Eric Dumazet <eric.dumazet@gmail.com> - 2015-11-11 14:40 +0100
            Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 14:50 +0100
              Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller Eric Dumazet <eric.dumazet@gmail.com> - 2015-11-11 15:10 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 15:20 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 15:40 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller Eric Dumazet <eric.dumazet@gmail.com> - 2015-11-11 15:50 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller Eric Dumazet <eric.dumazet@gmail.com> - 2015-11-11 15:50 +0100
          Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 17:30 +0100
            Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 19:30 +0100
              Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 20:10 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 20:20 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 20:20 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 20:30 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 20:30 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 20:40 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 20:50 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 21:50 +0100
                Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller Måns Rullgård <mans@mansr.com> - 2015-11-11 20:30 +0100
              Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 20:10 +0100
        Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800  Ethernet controller David Miller <davem@davemloft.net> - 2015-11-11 17:30 +0100

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