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Re: [RFC PATCH 0/2] net: threadable napi poll loop

From Hannes Frederic Sowa <hannes@stressinduktion.org>
Newsgroups linux.kernel
Subject Re: [RFC PATCH 0/2] net: threadable napi poll loop
Date 2016-05-12 00:50 +0200
Message-ID <rxL74-U4-35@gated-at.bofh.it> (permalink)
References (5 earlier) <rxoNc-3DI-3@gated-at.bofh.it> <rxyWe-5Bh-7@gated-at.bofh.it> <rxC3M-to-15@gated-at.bofh.it> <rxDsS-1yk-1@gated-at.bofh.it> <rxDCy-1G3-5@gated-at.bofh.it>
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On 11.05.2016 16:45, Eric Dumazet wrote:
> On Wed, May 11, 2016 at 7:38 AM, Paolo Abeni <pabeni@redhat.com> wrote:
> 
>> Uh, we have likely the same issue in the net_rx_action() function, which
>> also execute with bh disabled and check for jiffies changes even on
>> single core hosts ?!?
> 
> That is why we have a loop break after netdev_budget=300 packets.
> And a sysctl to eventually tune this.
> 
> Same issue for softirq handler, look at commit
> 34376a50fb1fa095b9d0636fa41ed2e73125f214
> 
> Your questions about this central piece of networking code are worrying.
> 
>>
>> Aren't jiffies updated by the timer interrupt ? and thous even with
>> bh_disabled ?!?
> 
> Exactly my point : jiffie wont be updated in your code, since you block BH.

To be fair, jiffies get updated in hardirq and not softirq context. The
cond_resched_softirq not looking for pending softirqs is indeed a problem.

Thanks,
Hannes

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Thread

[RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-10 16:20 +0200
  [RFC PATCH 2/2] net: add sysfs attribute to control napi threaded mode Paolo Abeni <pabeni@redhat.com> - 2016-05-10 16:20 +0200
  Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-10 16:40 +0200
    Re: [RFC PATCH 0/2] net: threadable napi poll loop David Miller <davem@davemloft.net> - 2016-05-10 18:00 +0200
    Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-10 18:10 +0200
      Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-10 22:30 +0200
        Re: [RFC PATCH 0/2] net: threadable napi poll loop David Miller <davem@davemloft.net> - 2016-05-10 22:50 +0200
          Re: [RFC PATCH 0/2] net: threadable napi poll loop David Miller <davem@davemloft.net> - 2016-05-10 23:00 +0200
            Re: [RFC PATCH 0/2] net: threadable napi poll loop Rik van Riel <riel@redhat.com> - 2016-05-10 23:10 +0200
          Re: [RFC PATCH 0/2] net: threadable napi poll loop Rik van Riel <riel@redhat.com> - 2016-05-10 23:00 +0200
    Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-10 18:10 +0200
    Re: [RFC PATCH 0/2] net: threadable napi poll loop Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-05-10 22:50 +0200
      Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <edumazet@google.com> - 2016-05-10 23:10 +0200
        Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-10 23:40 +0200
          Re: [RFC PATCH 0/2] net: threadable napi poll loop Rik van Riel <riel@redhat.com> - 2016-05-10 23:40 +0200
            Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 00:00 +0200
              Re: [RFC PATCH 0/2] net: threadable napi poll loop Rik van Riel <riel@redhat.com> - 2016-05-11 00:10 +0200
              Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 00:10 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 00:50 +0200
              Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 20:00 +0200
        Re: [RFC PATCH 0/2] net: threadable napi poll loop Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-05-11 00:40 +0200
          Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 01:00 +0200
            Re: [RFC PATCH 0/2] net: threadable napi poll loop Peter Zijlstra <peterz@infradead.org> - 2016-05-11 09:00 +0200
              Re: [RFC PATCH 0/2] net: threadable napi poll loop Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-05-11 15:20 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <edumazet@google.com> - 2016-05-11 16:50 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Rik van Riel <riel@redhat.com> - 2016-05-11 17:10 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 18:00 +0200
              Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-12 00:00 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-12 22:10 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-12 22:50 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-12 23:00 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-12 23:10 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-13 19:00 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <edumazet@google.com> - 2016-05-13 19:10 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-13 19:20 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <edumazet@google.com> - 2016-05-13 19:40 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-16 15:20 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <edumazet@google.com> - 2016-05-16 15:40 +0200
            Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-11 11:50 +0200
              Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <eric.dumazet@gmail.com> - 2016-05-11 15:10 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-05-11 15:40 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-05-11 15:50 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-11 16:40 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet <edumazet@google.com> - 2016-05-11 16:50 +0200
                Re: [RFC PATCH 0/2] net: threadable napi poll loop Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-05-12 00:50 +0200
  Re: [RFC PATCH 0/2] net: threadable napi poll loop Thomas Gleixner <tglx@linutronix.de> - 2016-05-10 18:00 +0200
    Re: [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni <pabeni@redhat.com> - 2016-05-10 22:50 +0200

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