linux-kernel - Re: [PATCHv11 3/4] genirq: Avoid summation loops for /proc/interrupts

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Message-ID: <CAD=FV=W7gOpLw2VwRO7EwwNoqSJFM8iC0-R1GC4RHtz4=fwa5A@mail.gmail.com>
Date: Wed, 28 Feb 2024 14:44:50 -0800
From: Doug Anderson <dianders@...omium.org>
To: Bitao Hu <yaoma@...ux.alibaba.com>
Cc: tglx@...utronix.de, liusong@...ux.alibaba.com, akpm@...ux-foundation.org, 
	pmladek@...e.com, kernelfans@...il.com, deller@....de, npiggin@...il.com, 
	tsbogend@...ha.franken.de, James.Bottomley@...senpartnership.com, 
	jan.kiszka@...mens.com, linux-kernel@...r.kernel.org, 
	linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCHv11 3/4] genirq: Avoid summation loops for /proc/interrupts

Hi,

On Tue, Feb 27, 2024 at 11:22 PM Bitao Hu <yaoma@...ux.alibaba.com> wrote:
>
> show_interrupts() unconditionally accumulates the per CPU interrupt
> statistics to determine whether an interrupt was ever raised.
>
> This can be avoided for all interrupts which are not strictly per CPU
> and not of type NMI because those interrupts provide already an
> accumulated counter. The required logic is already implemented in
> kstat_irqs().
>
> Split the inner access logic out of kstat_irqs() and use it for
> kstat_irqs() and show_interrupts() to avoid the accumulation loop
> when possible.
>
> Originally-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Bitao Hu <yaoma@...ux.alibaba.com>
> Reviewed-by: Liu Song <liusong@...ux.alibaba.com>
> ---
>  kernel/irq/internals.h |  2 ++
>  kernel/irq/irqdesc.c   | 16 +++++++++++-----
>  kernel/irq/proc.c      |  6 ++----
>  3 files changed, 15 insertions(+), 9 deletions(-)

Reviewed-by: Douglas Anderson <dianders@...omium.org>