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Date: Thu, 29 Mar 2012 15:48:34 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: David Sharp <dhsharp@google.com>
CC: Vaibhav Nagarnaik <vnagarnaik@google.com>, Ingo Molnar <mingo@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        Justin Teravest <teravest@google.com>,
        Laurent Chavey <chavey@google.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/6] trace: trace syscall in its handler not from ptrace
 handler
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On 03/29/2012 03:44 PM, David Sharp wrote:
>>
>> ANY increase to the fastpath is unacceptable, period.
> 
> I think the last 4 ns would probably be eliminated if we could figure
> out how to call the inline function trace_sys_enter directly instead
> of through the out-of-line wrapper we had to add to work around the
> preprocessor magic.

I already told you how to do it... override the system call table entry.
 There is a nice, juicy FUNCTION POINTER that we indirect through.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.