From: Ingo Molnar <mingo@elte.hu>
To: Kevin Hilman <kevin@hilman.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Real-Time Preemption and GFP_ATOMIC
Date: Thu, 10 Feb 2005 16:59:28 +0100 [thread overview]
Message-ID: <20050210155928.GA8263@elte.hu> (raw)
In-Reply-To: <83r7jyiyqx.fsf@www2.muking.org>
* Kevin Hilman <kevin@hilman.org> wrote:
> To produce the following trace, I wrote a simple moudle which just has
> this as its init_module routine:
>
> local_irq_disable();
> p = __get_free_page(GFP_ATOMIC);
> local_irq_enable();
in the PREEMPT_RT kernel almost everything might sleep, so the general
rule is to not call anything 'complex' from an IRQs-off section.
Depending on which is easier in your code, if you want to fix it up for
PREEMPT_RT then either move the GFP_ATOMIC allocation from under the
irqs-off section, or introduce a spinlock for the irqs-off section and
use spin_lock_irqsave(). (that is almost always needed anyway if you
really needed the irqs-off section.)
Ingo
prev parent reply other threads:[~2005-02-10 15:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-02 18:48 Kevin Hilman
2005-02-02 21:30 ` Esben Nielsen
2005-02-10 15:59 ` Ingo Molnar [this message]
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