From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/5] perf events: add support for realtime clock
 attribute
Date: Sun, 20 Mar 2011 20:08:10 +0100 (CET)
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To: David Ahern <daahern@cisco.com>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, acme@ghostprotocols.net, mingo@elte.hu, peterz@infradead.org, fweisbec@gmail.com, paulus@samba.org

On Sun, 20 Mar 2011, David Ahern wrote:
> +
> +	if (sample_type & PERF_SAMPLE_REALTIME)
> +		data->realtime = ktime_to_ns(ktime_get_real());

That's going to live lock on any sample which happens to hit in a
xtime_lock write locked section. I knew why I suggested adding
tracepoints to the timekeeping code :)

Thanks,

	tglx