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From: "Cédric Le Goater" <clg@kaod.org>
To: Thomas Gleixner <tglx@linutronix.de>,
	Nicholas Piggin <npiggin@gmail.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] genirq: reduce irqdebug bouncing cachelines
Date: Wed, 14 Apr 2021 15:13:14 +0200	[thread overview]
Message-ID: <8f7b2768-fe69-b1eb-8fc0-dc77a394ae99@kaod.org> (raw)
In-Reply-To: <87tuoax79f.ffs@nanos.tec.linutronix.de>

On 4/13/21 10:24 PM, Thomas Gleixner wrote:
> On Tue, Apr 13 2021 at 14:16, Cédric Le Goater wrote:
>>>> We could test irq_settings_no_debug() directly under handle_nested_irq() 
>>>> and handle_irq_event_percpu() to avoid calling note_interrupt(), just 
>>>> like we do for noirqdebug.
>>>
>>> We can do that, but then we should not just make it:
>>>
>>>    if (!irqnodebug && !irq_settings_no_debug(desc))
>>>    	note_interrupt(...);
>>>
>>> Instead have only one condition:
>>>
>>>    if (!irq_settings_no_debug(desc))
>>>    	note_interrupt(...);
>>>
>>> See the uncompiled delta patch below.
>>
>> I merged this second part with the first and gave IRQF_NO_DEBUG a try 
>> on P8 and P9 systems and all looked fine. I should send both patches 
>> after IRQF_NO_AUTOEN is merged in mainline.     
> 
> Does having that NODEBUG flag set on the IPI irqs make a measurable
> difference or is it just too small to matter?

It does not add much benefits on the 2s and 4s systems but I will give it 
a try on bigger ones when I can grab them. Then we can decide if it is 
worth merging. 

Thanks,

C.

  reply	other threads:[~2021-04-14 13:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-02 13:20 [PATCH] genirq: reduce irqdebug bouncing cachelines Nicholas Piggin
2021-04-10 11:38 ` [tip: irq/core] genirq: Reduce irqdebug cacheline bouncing tip-bot2 for Nicholas Piggin
2021-04-10 11:58 ` [PATCH] genirq: reduce irqdebug bouncing cachelines Thomas Gleixner
2021-04-12  9:06   ` Cédric Le Goater
2021-04-12 12:43     ` Thomas Gleixner
2021-04-13 12:16       ` Cédric Le Goater
2021-04-13 20:24         ` Thomas Gleixner
2021-04-14 13:13           ` Cédric Le Goater [this message]
2021-05-15 17:01           ` Cédric Le Goater
2021-05-17 18:04             ` [tip: irq/core] genirq: Add a IRQF_NO_DEBUG flag tip-bot2 for Thomas Gleixner

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