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Date: Thu, 05 Dec 2013 17:10:57 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>, Alexei Starovoitov <ast@plumgrid.com>
CC: Ingo Molnar <mingo@kernel.org>, Steven Rostedt <rostedt@goodmis.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Thomas Gleixner <tglx@linutronix.de>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Tom Zanussi <tom.zanussi@linux.intel.com>,
        Jovi Zhangwei <jovi.zhangwei@gmail.com>,
        Eric Dumazet <edumazet@google.com>, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH tip 0/5] tracing filters with BPF
References: <1386044930-15149-1-git-send-email-ast@plumgrid.com> <87fvq9cwlk.fsf@tassilo.jf.intel.com> <CAMEtUuzweYxqwoaYH+J5a2uRM+PFcBH+Pb8Z_ALPUMp+QFz1tQ@mail.gmail.com> <CAMEtUuzWLcTOeQSrhEQHVn7DbuoJn7bNek9-toQ9xZYzya3-ag@mail.gmail.com> <20131206001454.GB21717@two.firstfloor.org>
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On 12/05/2013 04:14 PM, Andi Kleen wrote:
> 
> In my experience there are roughly two groups of trace users:
> kernel hackers and users. The kernel hackers want something
> convenient and fast, but for anything complicated or performance
> critical they can always hack the kernel to include custom 
> instrumentation.
> 

Not to mention that in that case we might as well -- since we need a
compiler anyway -- generate the machine code in user space; the JIT
solution really only is useful if it can provide something that we can't
do otherwise, e.g. enable it in secure boot environments.

	-hpa