Re: [PATCH 4/6] trace: trace syscall in its handler not from ptracehandler
From: H. Peter Anvin
Date: Thu Mar 29 2012 - 18:48:49 EST
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.
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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