From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH-v3] tty: Use raw spin lock to protect the TTY read
 section
Date: Mon, 4 Feb 2013 16:33:33 +0100 (CET)
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Cc: linux-serial@vger.kernel.org, RT <linux-rt-users@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Greg KH <gregkh@linuxfoundation.org>
To: Ivo Sieben <meltedpianoman@gmail.com>
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On Mon, 28 Jan 2013, Ivo Sieben wrote:
> @Thomas Gleixner & Steven Rostedt:
> Greg Kroah-Hartman responded to this patch: "And this really makes a
> difference? I'd like to hear the rt developers opinion of this."

In general the sleeping spinlocks overhead can be quite visible and
AFAICT the ntty read_lock only protects very short code pathes which
manipulate the read buffer and related data. So from an RT perspective
this lock can be a real spinlock even on RT.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Thanks,

	tglx