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

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Message-ID: <1462978903.7134.33.camel@redhat.com>
Date:	Wed, 11 May 2016 11:01:43 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Eric Dumazet <edumazet@...gle.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Paolo Abeni <pabeni@...hat.com>,
	netdev <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Jiri Pirko <jiri@...lanox.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Alexander Duyck <aduyck@...antis.com>,
	Tom Herbert <tom@...bertland.com>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/2] net: threadable napi poll loop

On Wed, 2016-05-11 at 07:40 -0700, Eric Dumazet wrote:
> On Wed, May 11, 2016 at 6:13 AM, Hannes Frederic Sowa
> <hannes@...essinduktion.org> wrote:
> 
> > This looks racy to me as the ksoftirqd could be in the progress to
> > stop
> > and we would miss another softirq invocation.
> 
> Looking at smpboot_thread_fn(), it looks fine :
> 

Additionally, we are talking about waking up
ksoftirqd on the same CPU.

That means the wakeup code could interrupt
ksoftirqd almost going to sleep, but the
two code paths could not run simultaneously.

That does narrow the scope considerably.

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