Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1399065

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 2016-05-11 15:20 +0200
Message-ID <rxCds-zl-1@gated-at.bofh.it> (permalink)
References (2 earlier) <rxmLo-1CV-7@gated-at.bofh.it> <rxn4J-2dm-1@gated-at.bofh.it> <rxotQ-3v7-1@gated-at.bofh.it> <rxoNc-3DI-3@gated-at.bofh.it> <rxwhH-2Pr-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

On 11.05.2016 08:55, Peter Zijlstra wrote:
> On Tue, May 10, 2016 at 03:51:37PM -0700, Eric Dumazet wrote:
>> diff --git a/kernel/softirq.c b/kernel/softirq.c
>> index 17caf4b63342..22463217e3cf 100644
>> --- a/kernel/softirq.c
>> +++ b/kernel/softirq.c
>> @@ -56,6 +56,7 @@ EXPORT_SYMBOL(irq_stat);
>>  static struct softirq_action softirq_vec[NR_SOFTIRQS] __cacheline_aligned_in_smp;
>>  
>>  DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
>> +DEFINE_PER_CPU(bool, ksoftirqd_scheduled);
>>  
>>  const char * const softirq_to_name[NR_SOFTIRQS] = {
>>  	"HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL",
>> @@ -73,8 +74,10 @@ static void wakeup_softirqd(void)
>>  	/* Interrupts are disabled: no need to stop preemption */
>>  	struct task_struct *tsk = __this_cpu_read(ksoftirqd);
>>  
>> -	if (tsk && tsk->state != TASK_RUNNING)
>> +	if (tsk && tsk->state != TASK_RUNNING) {
>> +		__this_cpu_write(ksoftirqd_scheduled, true);
>>  		wake_up_process(tsk);
> 
> Since we're already looking at tsk->state, and the wake_up_process()
> ensures the thing becomes TASK_RUNNING, you could add:
> 
> static inline bool ksoftirqd_running(void)
> {
> 	return __this_cpu_read(ksoftirqd)->state == TASK_RUNNING;
> }

This looks racy to me as the ksoftirqd could be in the progress to stop
and we would miss another softirq invocation.

Thanks,
Hannes

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

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> - 2016-05-11 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

csiph-web