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From: Thomas Gleixner <tglx@linutronix.de>
To: Jakub Kicinski <kuba@kernel.org>, davem@davemloft.net
Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com,
	simon.horman@netronome.com, oss-drivers@netronome.com,
	bigeasy@linutronix.de, Jakub Kicinski <kuba@kernel.org>
Subject: Re: [PATCH net-next 1/2] net: add a napi variant for RT-well-behaved drivers
Date: Sat, 15 May 2021 11:49:02 +0200	[thread overview]
Message-ID: <87pmxs1g4x.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210514222402.295157-1-kuba@kernel.org>

On Fri, May 14 2021 at 15:24, Jakub Kicinski wrote:
>  /**
> - *	napi_schedule_irqoff - schedule NAPI poll
> - *	@n: NAPI context
> + * napi_schedule_irq() - schedule NAPI poll from hardware IRQ
> + * @n: NAPI context
>   *
>   * Variant of napi_schedule(), assuming hard irqs are masked.
> + * Hardware interrupt handler must be marked with IRQF_NO_THREAD
> + * to safely invoke this function on CONFIG_RT=y kernels (unless
> + * it manually masks the interrupts already).
>   */
> -static inline void napi_schedule_irqoff(struct napi_struct *n)
> +static inline void napi_schedule_irq(struct napi_struct *n)
>  {
>  	if (napi_schedule_prep(n))
> -		__napi_schedule_irqoff(n);
> +		__napi_schedule_irq(n);

As this is intended for the trivial

   irqhandler()
        napi_schedule_irq(n);
        return IRQ_HANDLED;

case, wouldn't it make sense to bring napi_schedule_irq() out of line
and have the prep invocation right there?

void napi_schedule_irq(struct napi_struct *n)
{
 	if (napi_schedule_prep(n))
		____napi_schedule(this_cpu_ptr(&softnet_data), n);
}
EXPORT_SYMBOL(napi_schedule_irq);

As that spares a function call and lets the compiler be smarter about
it. I might be missing something though, but at least brain is more
awake now :)

Thanks,

        tglx

  parent reply	other threads:[~2021-05-15  9:49 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-14 22:24 Jakub Kicinski
2021-05-14 22:24 ` [PATCH net-next 2/2] nfp: use napi_schedule_irq() Jakub Kicinski
2021-05-17  9:48   ` Simon Horman
2021-05-15  0:17 ` [PATCH net-next 1/2] net: add a napi variant for RT-well-behaved drivers Thomas Gleixner
2021-05-15  0:21   ` Jakub Kicinski
2021-05-15  0:29     ` Thomas Gleixner
2021-05-15  9:49 ` Thomas Gleixner [this message]
2021-05-15 20:38   ` Jakub Kicinski
2021-05-15 11:07 ` Sebastian Andrzej Siewior
2021-05-15 20:31   ` Jakub Kicinski
2021-05-15 20:53     ` Thomas Gleixner
2021-05-21 14:11       ` Juri Lelli

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