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From: Will Deacon <will@kernel.org>
To: "Bouska, Zdenek" <zdenek.bouska@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Kiszka, Jan" <jan.kiszka@siemens.com>,
	"linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
	Nishanth Menon <nm@ti.com>, Puranjay Mohan <p-mohan@ti.com>
Subject: Re: Unfair qspinlocks on ARM64 without LSE atomics => 3ms delay in interrupt handling
Date: Thu, 27 Apr 2023 11:06:57 +0100	[thread overview]
Message-ID: <20230427100656.GA10855@willie-the-truck> (raw)
In-Reply-To: <AS1PR10MB5675F26ADC112F008B52F195EB6A9@AS1PR10MB5675.EURPRD10.PROD.OUTLOOK.COM>

On Thu, Apr 27, 2023 at 09:38:59AM +0000, Bouska, Zdenek wrote:
> > Why is this interrupt handling specific? Just because it's the place
> > where you observed it?
> Yes.
> 
> > So if that helps, then this needs to be addressed globaly and not with
> > some crude hack in the interrupt handling code.
> I just wrote, what helps for me. I didn't mean it as a proposal for merge.
> Sorry for confusion.
> 
> I tried using Will's cpu_relax() implementation [1] everywhere but I was not 
> successful with that yet. ARM64's VDSO makes it complicating and even
> if I left original cpu_relax() just in VDSO, Linux did not boot for me.

It definitely seemed to work when I posted it all those years ago, but I'm
not surprised if it needs some TLC to revive it on more recent kernels.

Will

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: "Bouska, Zdenek" <zdenek.bouska@siemens.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Kiszka, Jan" <jan.kiszka@siemens.com>,
	"linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
	Nishanth Menon <nm@ti.com>, Puranjay Mohan <p-mohan@ti.com>
Subject: Re: Unfair qspinlocks on ARM64 without LSE atomics => 3ms delay in interrupt handling
Date: Thu, 27 Apr 2023 11:06:57 +0100	[thread overview]
Message-ID: <20230427100656.GA10855@willie-the-truck> (raw)
In-Reply-To: <AS1PR10MB5675F26ADC112F008B52F195EB6A9@AS1PR10MB5675.EURPRD10.PROD.OUTLOOK.COM>

On Thu, Apr 27, 2023 at 09:38:59AM +0000, Bouska, Zdenek wrote:
> > Why is this interrupt handling specific? Just because it's the place
> > where you observed it?
> Yes.
> 
> > So if that helps, then this needs to be addressed globaly and not with
> > some crude hack in the interrupt handling code.
> I just wrote, what helps for me. I didn't mean it as a proposal for merge.
> Sorry for confusion.
> 
> I tried using Will's cpu_relax() implementation [1] everywhere but I was not 
> successful with that yet. ARM64's VDSO makes it complicating and even
> if I left original cpu_relax() just in VDSO, Linux did not boot for me.

It definitely seemed to work when I posted it all those years ago, but I'm
not surprised if it needs some TLC to revive it on more recent kernels.

Will

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  reply	other threads:[~2023-04-27 10:07 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-26 12:03 Unfair qspinlocks on ARM64 without LSE atomics => 3ms delay in interrupt handling Bouska, Zdenek
2023-04-26 21:29 ` Thomas Gleixner
2023-04-26 21:29   ` Thomas Gleixner
2023-04-27  9:38   ` Bouska, Zdenek
2023-04-27  9:38     ` Bouska, Zdenek
2023-04-27 10:06     ` Will Deacon [this message]
2023-04-27 10:06       ` Will Deacon
2023-04-27 13:14   ` Jan Kiszka
2023-04-27 13:14     ` Jan Kiszka
2023-04-27 13:45     ` Kurt Kanzenbach
2023-04-27 13:45       ` Kurt Kanzenbach
2023-04-28  7:30       ` Sebastian Andrzej Siewior
2023-04-28  7:30         ` Sebastian Andrzej Siewior
2023-04-28  7:37         ` Kurt Kanzenbach
2023-04-28  7:37           ` Kurt Kanzenbach
  -- strict thread matches above, loose matches on Subject: below --
2023-03-24  8:43 Bouska, Zdenek
2023-03-24  8:43 ` Bouska, Zdenek
2023-03-24 17:01 ` Catalin Marinas
2023-03-24 17:01   ` Catalin Marinas
2023-03-24 18:09   ` Will Deacon
2023-03-24 18:09     ` Will Deacon
2023-03-28  9:39     ` Bouska, Zdenek
2023-03-28  9:39       ` Bouska, Zdenek
2023-03-27  5:44   ` Bouska, Zdenek
2023-03-27  5:44     ` Bouska, Zdenek

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