linux-kernel - Re: [PATCH 0/6] Optimize the cpu hotplug locking -v2

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Message-ID: <20131011135114.24362.qmail@science.horizon.com>
Date:	11 Oct 2013 09:51:14 -0400
From:	"George Spelvin" <linux@...izon.com>
To:	linux@...izon.com, rostedt@...dmis.org
Cc:	linux-kernel@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
	peterz@...radead.org, srivatsa.bhat@...ux.vnet.ibm.com,
	torvalds@...ux-foundation.org
Subject: Re: [PATCH 0/6] Optimize the cpu hotplug locking -v2

> The problem is that the scheduler doesn't see that the current task has
> preemption disabled. It only looks at the priorities of the current
> task, and if it can preempt it, it will. It sets the NEED_RESCHED to the
> current task and waits for the preemption to schedule it out.

Ah, got it.  It's a priority inversion problem, and while there is a
standard solution (priority inheritance), if I were to suggest such a
heavyweight solution, Linus would start yelling again and Sarah would
get unhappy, and we all know how that ends up.

Thank you.  I will now cease displaying my ignorance in public.
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