Message-ID: <502444CC.8030906@linux.intel.com>
Date: Thu, 09 Aug 2012 16:16:28 -0700
From: "H. Peter Anvin" <hpa@linux.intel.com>
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To: Steven Rostedt <rostedt@goodmis.org>
CC: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Avi Kivity <avi@redhat.com>, Christoph Hellwig <hch@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH] tracepoints: Move the work out of line from hotpath
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On 08/09/2012 03:25 PM, Steven Rostedt wrote:
>>
>> It might be better to improve gcc to move really cold branches out of
>> line (really, really far away), and use the compiler to do this, rather
>> than to use an extra indirection that adds bloat and complexity to the
>> kernel.
> 
> I think modifying gcc is something that can help more than tracing. But
> that's been a pipe dream for such a long time that I've started dreaming
> about winning a gold medal in the Olympics instead. Standing on the
> podium listening to the crowd chanting your name along with your country
> is more fun to dream about than seeing your unlikely code stop becoming
> hurdles for the CPU sprinters.
> 

At one point, maybe, but lately we have had a lot more traction from the
gcc developers, giving us features like __fentry__ and asm goto.

	-hpa

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