From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Bouska, Zdenek" <zdenek.bouska@siemens.com>,
Will Deacon <will@kernel.org>,
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>,
"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: Fri, 28 Apr 2023 09:30:16 +0200 [thread overview]
Message-ID: <20230428073016.YfrIGGoN@linutronix.de> (raw)
In-Reply-To: <871qk5782i.fsf@kurt>
On 2023-04-27 15:45:09 [+0200], Kurt Kanzenbach wrote:
> > Are we aware of other concrete case where it bites? Even with just
> > "normal" contented spin_lock usage?
>
> Well, some years ago I've observed a similar problem with ARM64
> spinlocks, cpu_relax() and retry loops (in the futex code). It also
> generated latency spikes up to 2-3ms. Back then, it was easily
> reproducible using stress-ng --ptrace 4.
That was fixed by
https://patchwork.kernel.org/project/linux-arm-kernel/patch/1399528508-2806-1-git-send-email-arjun.kv@samsung.com
if my memory serves me well.
> Thanks,
> Kurt
Sebastian
WARNING: multiple messages have this Message-ID (diff)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Bouska, Zdenek" <zdenek.bouska@siemens.com>,
Will Deacon <will@kernel.org>,
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>,
"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: Fri, 28 Apr 2023 09:30:16 +0200 [thread overview]
Message-ID: <20230428073016.YfrIGGoN@linutronix.de> (raw)
In-Reply-To: <871qk5782i.fsf@kurt>
On 2023-04-27 15:45:09 [+0200], Kurt Kanzenbach wrote:
> > Are we aware of other concrete case where it bites? Even with just
> > "normal" contented spin_lock usage?
>
> Well, some years ago I've observed a similar problem with ARM64
> spinlocks, cpu_relax() and retry loops (in the futex code). It also
> generated latency spikes up to 2-3ms. Back then, it was easily
> reproducible using stress-ng --ptrace 4.
That was fixed by
https://patchwork.kernel.org/project/linux-arm-kernel/patch/1399528508-2806-1-git-send-email-arjun.kv@samsung.com
if my memory serves me well.
> Thanks,
> Kurt
Sebastian
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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-04-28 7:30 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
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 [this message]
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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