netdev - Re: [PATCH net-next] net/core: disable NET_RX_BUSY_POLL on PREEMPT

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Message-Id: <163312860747.19403.5188764825013993670.git-patchwork-notify@kernel.org>
Date:   Fri, 01 Oct 2021 22:50:07 +0000
From:   patchwork-bot+netdevbpf@...nel.org
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        tglx@...utronix.de
Subject: Re: [PATCH net-next] net/core: disable NET_RX_BUSY_POLL on PREEMPT_RT

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Fri,  1 Oct 2021 16:58:41 +0200 you wrote:
> napi_busy_loop() disables preemption and performs a NAPI poll. We can't acquire
> sleeping locks with disabled preemption which would be required while
> __napi_poll() invokes the callback of the driver.
> 
> A threaded interrupt performing the NAPI-poll can be preempted on PREEMPT_RT.
> A RT thread on another CPU may observe NAPIF_STATE_SCHED bit set and busy-spin
> until it is cleared or its spin time runs out. Given it is the task with the
> highest priority it will never observe the NEED_RESCHED bit set.
> In this case the time is better spent by simply sleeping.
> 
> [...]

Here is the summary with links:
  - [net-next] net/core: disable NET_RX_BUSY_POLL on PREEMPT_RT
    https://git.kernel.org/netdev/net-next/c/20ab39d13e2e

You are awesome, thank you!
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