[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <AD975D71AAD7784D8D1265DF6444C2FD0132AD51@storexdag03.amd.com>
Date: Mon, 31 Mar 2014 10:38:12 +0000
From: "Skidanov, Alexey" <Alexey.Skidanov@....com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "Gabbay, Oded" <Oded.Gabbay@....com>
Subject: CONFIG_PREEMPT_COUNT
Hello,
I found that preempt_enable() and preempt_disable() macros are defined differently depending on CONFIG_PREEMPT_COUNT:
- They increment per CPU preemption counter, if CONFIG_PREEMPT_COUNT defined
- They do nothing (just call barrier), if not.
I have it undefined in my source tree.
The questions are:
1. What is the purpose of CONFIG_PREEMPT_COUNT define and how I can define it?
2. In the previous kernel versions, spin_lock() and spin_unlock() call preempt_enable() and preempt_disable() respectively, ensuring that the current task will not be preempted by any other task while lock is held. Is this still ensured with these macros defined as "do nothing" ?
Thanks
Alexey
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists