linux-kernel - Re: [PATCH v3 net-next] net: link_watch: prevent starvation when processing linkwatch wq

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Message-Id: <20190701.190310.2238828290259478075.davem@davemloft.net>
Date:   Mon, 01 Jul 2019 19:03:10 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     linyunsheng@...wei.com
Cc:     hkallweit1@...il.com, gregkh@...uxfoundation.org,
        tglx@...utronix.de, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, pbonzini@...hat.com,
        rkrcmar@...hat.com, kvm@...r.kernel.org
Subject: Re: [PATCH v3 net-next] net: link_watch: prevent starvation when
 processing linkwatch wq

From: Yunsheng Lin <linyunsheng@...wei.com>
Date: Fri, 28 Jun 2019 09:13:19 +0800

> 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 rtnl locking starvation problem and worker
> starvation problem for other work queue, such as irqfd_inject wq.
> 
> 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>
> ---
> V2: use cond_resched and rtnl_unlock after processing a fixed
>     number of events
> V3: fall back to v1 and change commit log to reflect that.

Applied, thanks.