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    SubjectRe: Benchmarks of kernel tracing options 2 (ftrace, lttng and perf)
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    On Wed, 2010-11-17 at 15:22 -0800, David Sharp wrote:
    > On Wed, Nov 17, 2010 at 2:56 PM, Douglas Santos
    > <douglas.santos@polymtl.ca> wrote:
    > > Quoting Steven Rostedt <rostedt@goodmis.org>:
    > >> On Wed, 2010-11-17 at 16:31 -0500, Douglas Santos wrote:
    > >> > Hi all,
    > >> >
    > >> > This is a response to a benchmark, submitted a few weeks ago, comparing
    > >> kernel
    > >> > tracing options.
    > >> > http://lkml.org/lkml/2010/10/28/422
    > >> >
    > >> > We followed the methodology described in the link bellow,
    > >> > but using the shellscripts posted there to reproduce autotest scripts.
    > >> > http://lkml.org/lkml/2010/10/28/261
    > >> >
    > >> > We disabled the extra syscall tracing on lttng, for a fair comparison.
    > >> > http://lkml.org/lkml/2010/10/28/290
    > >> >
    > >> > Average results with tracing "on":
    > >> >
    > >> > lttng: 220 ns
    > >> > ftrace: 260 ns
    > >>
    > >> Heh, so ftrace got worse with the new kernel?
    >
    > Steve, can you explain how you're drawing that conclusion? Did Douglas
    > run this benchmark before on a previous kernel (I didn't see it if
    > so)?

    Oops, no, I was thinking that this was from your tests. I remember
    asking you to try the new kernel. I think I got you and Douglas
    confused :-)

    -- Steve




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