From: Peter Zijlstra <peterz@infradead•org>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion•org>,
Eric Dumazet <edumazet@google•com>,
Paolo Abeni <pabeni@redhat•com>, netdev <netdev@vger•kernel.org>,
"David S. Miller" <davem@davemloft•net>,
Jiri Pirko <jiri@mellanox•com>,
Daniel Borkmann <daniel@iogearbox•net>,
Alexei Starovoitov <ast@plumgrid•com>,
Alexander Duyck <aduyck@mirantis•com>,
Tom Herbert <tom@herbertland•com>, Ingo Molnar <mingo@kernel•org>,
Rik van Riel <riel@redhat•com>,
LKML <linux-kernel@vger•kernel.org>
Subject: Re: [RFC PATCH 0/2] net: threadable napi poll loop
Date: Wed, 11 May 2016 08:55:27 +0200 [thread overview]
Message-ID: <20160511065527.GD3193@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1462920697.23934.113.camel@edumazet-glaptop3.roam.corp.google.com>
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;
}
> + }
> }
>
> /*
> @@ -162,7 +165,9 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
> */
> preempt_count_sub(cnt - 1);
>
> - if (unlikely(!in_interrupt() && local_softirq_pending())) {
> + if (unlikely(!in_interrupt() &&
> + local_softirq_pending() &&
> + !__this_cpu_read(ksoftirqd_scheduled))) {
And use it here,
> /*
> * Run softirq if any pending. And do it in its own stack
> * as we may be calling this deep in a task call stack already.
> @@ -340,6 +345,9 @@ void irq_enter(void)
>
> static inline void invoke_softirq(void)
> {
> + if (__this_cpu_read(ksoftirqd_scheduled))
and here.
> + return;
> +
> if (!force_irqthreads) {
> #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
> /*
> @@ -660,6 +668,8 @@ static void run_ksoftirqd(unsigned int cpu)
> * in the task stack here.
> */
> __do_softirq();
> + if (!local_softirq_pending())
> + __this_cpu_write(ksoftirqd_scheduled, false);
And avoid twiddling the new variable which only seems to mirror
tsk->state.
> local_irq_enable();
> cond_resched_rcu_qs();
> return;
>
>
next prev parent reply other threads:[~2016-05-11 6:55 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-10 14:11 [RFC PATCH 0/2] net: threadable napi poll loop Paolo Abeni
2016-05-10 14:11 ` [RFC PATCH 1/2] net: implement threaded-able napi poll loop support Paolo Abeni
2016-05-10 14:11 ` [RFC PATCH 2/2] net: add sysfs attribute to control napi threaded mode Paolo Abeni
2016-05-10 14:29 ` [RFC PATCH 0/2] net: threadable napi poll loop Eric Dumazet
2016-05-10 15:51 ` David Miller
2016-05-10 16:03 ` Paolo Abeni
2016-05-10 16:08 ` Eric Dumazet
2016-05-10 20:22 ` Paolo Abeni
2016-05-10 20:45 ` David Miller
2016-05-10 20:50 ` Rik van Riel
2016-05-10 20:52 ` David Miller
2016-05-10 21:01 ` Rik van Riel
2016-05-10 20:46 ` Hannes Frederic Sowa
2016-05-10 21:09 ` Eric Dumazet
2016-05-10 21:31 ` Eric Dumazet
2016-05-10 21:35 ` Rik van Riel
2016-05-10 21:53 ` Eric Dumazet
2016-05-10 22:02 ` Eric Dumazet
2016-05-10 22:44 ` Eric Dumazet
2016-05-10 22:02 ` Rik van Riel
2016-05-11 17:55 ` Eric Dumazet
2016-05-10 22:32 ` Hannes Frederic Sowa
2016-05-10 22:51 ` Eric Dumazet
2016-05-11 6:55 ` Peter Zijlstra [this message]
2016-05-11 13:13 ` Hannes Frederic Sowa
2016-05-11 14:40 ` Eric Dumazet
2016-05-11 15:01 ` Rik van Riel
2016-05-11 15:50 ` Eric Dumazet
2016-05-11 21:56 ` Eric Dumazet
2016-05-12 20:07 ` Paolo Abeni
2016-05-12 20:49 ` Eric Dumazet
2016-05-12 20:58 ` Paolo Abeni
2016-05-12 21:05 ` Eric Dumazet
2016-05-13 16:50 ` Paolo Abeni
2016-05-13 17:03 ` Eric Dumazet
2016-05-13 17:19 ` Paolo Abeni
2016-05-13 17:36 ` Eric Dumazet
2016-05-16 13:10 ` Paolo Abeni
2016-05-16 13:38 ` Eric Dumazet
2016-05-11 9:48 ` Paolo Abeni
2016-05-11 13:08 ` Eric Dumazet
2016-05-11 13:39 ` Hannes Frederic Sowa
2016-05-11 13:47 ` Hannes Frederic Sowa
2016-05-11 14:38 ` Paolo Abeni
2016-05-11 14:45 ` Eric Dumazet
2016-05-11 22:47 ` Hannes Frederic Sowa
2016-05-10 15:57 ` Thomas Gleixner
2016-05-10 20:41 ` Paolo Abeni
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160511065527.GD3193@twins.programming.kicks-ass.net \
--to=peterz@infradead$(echo .)org \
--cc=aduyck@mirantis$(echo .)com \
--cc=ast@plumgrid$(echo .)com \
--cc=daniel@iogearbox$(echo .)net \
--cc=davem@davemloft$(echo .)net \
--cc=edumazet@google$(echo .)com \
--cc=eric.dumazet@gmail$(echo .)com \
--cc=hannes@stressinduktion$(echo .)org \
--cc=jiri@mellanox$(echo .)com \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=mingo@kernel$(echo .)org \
--cc=netdev@vger$(echo .)kernel.org \
--cc=pabeni@redhat$(echo .)com \
--cc=riel@redhat$(echo .)com \
--cc=tom@herbertland$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox