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

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Message-ID: <1462896539.23934.93.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Tue, 10 May 2016 09:08:59 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Paolo Abeni <pabeni@...hat.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	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>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/2] net: threadable napi poll loop

On Tue, 2016-05-10 at 18:03 +0200, Paolo Abeni wrote:

> If a single core host is under network flood, i.e. ksoftirqd is
> scheduled and it eventually (after processing ~640 packets) will let the
> user space process run. The latter will execute a syscall to receive a
> packet, which will have to disable/enable bh at least once and that will
> cause the processing of another ~640 packets. To receive a single packet
> in user space, the kernel has to process more than one thousand packets.

Looks you found the bug then. Have you tried to fix it ?