linux-kernel - Re: [PATCH net-next] net: link_watch: prevent starvation when processing linkwatch wq

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Message-ID: <20190527075838.5a65abf9@hermes.lan>
Date:   Mon, 27 May 2019 07:58:38 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Yunsheng Lin <linyunsheng@...wei.com>
Cc:     <davem@...emloft.net>, <hkallweit1@...il.com>,
        <f.fainelli@...il.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>
Subject: Re: [PATCH net-next] net: link_watch: prevent starvation when
 processing linkwatch wq

On Mon, 27 May 2019 09:47:54 +0800
Yunsheng Lin <linyunsheng@...wei.com> wrote:

> When user has configured a large number of virtual netdev, such
> as 4K vlans, the carrier on/off operation of the real netdev
> will also cause it's virtual netdev's link state to be processed
> in linkwatch. Currently, the processing is done in a work queue,
> which may cause worker starvation problem for other work queue.
> 
> This patch releases the cpu when link watch worker has processed
> a fixed number of netdev' link watch event, and schedule the
> work queue again when there is still link watch event remaining.
> 
> Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>

Why not put link watch in its own workqueue so it is scheduled
separately from the system workqueue?