From: Steven Rostedt <rostedt@goodmis.org>
To: paulmck@us.ibm.com
Cc: shemminger@osdl.org, dipankar@in.ibm.com, mingo@elte.hu,
linux-kernel@vger.kernel.org
Subject: Re: PREEMPT/PREEMPT_RT question
Date: Tue, 12 Jul 2005 23:54:50 -0400 [thread overview]
Message-ID: <1121226890.3548.44.camel@localhost.localdomain> (raw)
In-Reply-To: <20050713014627.GF1323@us.ibm.com>
On Tue, 2005-07-12 at 18:46 -0700, Paul E. McKenney wrote:
> > If you are talking about scheduler_tick, then yes, it is called by the
> > timer interrupt which is a SA_NODELAY interrupt. If you don't want to
> > get interrupted by the timer interrupt, then you will need to disable
> > interrupts for both. Since currently, the timer interrupt is the only
> > true hard interrupt in the PREEMPT_RT and that may not change.
>
> OK, so if I take a spinlock in something invoked from scheduler_tick(),
> then any other acquisitions of that spinlock must disable hardware
> interrupts, right?
Yes, otherwise you could have a local CPU deadlock on a SMP machine. And
I would also say the same is true for any lock that is grabbed by the
timer interrupt or one of the functions it calls.
-- Steve
next prev parent reply other threads:[~2005-07-13 3:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-12 16:30 PREEMPT/PREEMPT_RT question Paul E. McKenney
2005-07-12 17:05 ` Steven Rostedt
2005-07-12 19:28 ` Paul E. McKenney
2005-07-12 20:04 ` Steven Rostedt
2005-07-12 21:34 ` Paul E. McKenney
2005-07-12 23:47 ` Steven Rostedt
2005-07-13 1:46 ` Paul E. McKenney
2005-07-13 3:54 ` Steven Rostedt [this message]
2005-07-13 15:41 ` Paul E. McKenney
2005-07-12 19:26 ` Ingo Molnar
2005-07-12 21:04 ` Paul E. McKenney
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