From: Jonas Oberhauser <jonas.oberhauser@huawei.com>
To: "paulmck@kernel.org" <paulmck@kernel.org>,
"riel@surriel.com" <riel@surriel.com>,
"davej@codemonkey.org.uk" <davej@codemonkey.org.uk>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kernel-team@meta.com" <kernel-team@meta.com>
Subject: RE: [PATCH diagnostic qspinlock] Diagnostics for excessive lock-drop wait loop time
Date: Thu, 12 Jan 2023 20:51:04 +0000 [thread overview]
Message-ID: <896a2d84918e4adc8a4d00d72510eb3d@huawei.com> (raw)
In-Reply-To: <20230112003627.GA3133092@paulmck-ThinkPad-P17-Gen-1>
Hi Paul,
-----Original Message-----
From: Paul E. McKenney [mailto:paulmck@kernel.org]
> We see systems stuck in the queued_spin_lock_slowpath() loop that waits for the lock to become unlocked in the case where the current CPU has set pending state.
Interesting!
Do you know if the hangs started with a recent patch? What codepaths are active (virtualization/arch/...)? Does it happen extremely rarely? Do you have any additional information?
I saw a similar situation a few years ago in a proprietary kernel, but it only happened once ever and I gave up on looking for the reason after a few days (including some time combing through the compiler generated assembler).
Have fun,
jonas
next prev parent reply other threads:[~2023-01-12 21:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-12 0:36 [PATCH diagnostic qspinlock] Diagnostics for excessive lock-drop wait loop time Paul E. McKenney
2023-01-12 20:51 ` Jonas Oberhauser [this message]
2023-01-12 23:49 ` Paul E. McKenney
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