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

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Message-ID: <CANn89i+YKrVOgfFwW-2psfCzq5_YLdmbV06-H-1FCOwXdMBuzQ@mail.gmail.com>
Date:	Tue, 10 May 2016 14:09:42 -0700
From:	Eric Dumazet <edumazet@...gle.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	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>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, Rik van Riel <riel@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/2] net: threadable napi poll loop

On Tue, May 10, 2016 at 1:46 PM, Hannes Frederic Sowa
<hannes@...essinduktion.org> wrote:

> I agree here, but I don't think this patch particularly is a lot of
> bloat and something very interesting people can play with and extend upon.
>

Sure, very rarely patch authors think their stuff is bloat.

I prefer to fix kernel softirq.c, or at least show me that you tried
hard enough.

I am pretty sure that the following would work :

When ksoftirqd is scheduled, remember this in a per cpu variable
(ksoftiqd_scheduled)

When enabling BH , do not call do_softirq() if this variable is set.

ksoftirqd would clear the variable at the right place (probably in
run_ksoftirqd())

Sure, this might add a lot of latency regressions, but lets fix them.