netdev - Re: [PATCH] hv_netvsc: remove ndo_poll

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Message-ID: <20180929145425.08f5a2e6@shemminger-XPS-13-9360>
Date:   Sat, 29 Sep 2018 14:54:25 +0200
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     netdev@...r.kernel.org
Cc:     Stephen Hemminger <sthemmin@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH] hv_netvsc: remove ndo_poll_controller

On Sat, 29 Sep 2018 14:52:56 +0200
Stephen Hemminger <stephen@...workplumber.org> wrote:

> Similar to other patches from ERic.
> 
> As diagnosed by Song Liu, ndo_poll_controller() can
> be very dangerous on loaded hosts, since the cpu
> calling ndo_poll_controller() might steal all NAPI
> contexts (for all RX/TX queues of the NIC). This capture
> can last for unlimited amount of time, since one
> cpu is generally not able to drain all the queues under load.
> 
> In netvsc driver it uses NAPI for TX completions. The default
> poll_napi will do this for us now and avoid the capture.
> 
> Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
> Cc: Haiyang Zhang <haiyangz@...rosoft.com>
> Cc: Eric Dumazet <edumazet@...gle.com>

Forgot to label this, it is for net-next.