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    SubjectRe: [PATCH 4/6] trace: trace syscall in its handler not from ptrace handler
    On Thu, Mar 29, 2012 at 12:12 PM, H. Peter Anvin <> wrote:
    > On 03/29/2012 12:02 PM, Vaibhav Nagarnaik wrote:
    >> Thanks for the feedback. I had missed this added latency due to this
    >> patch when tracing is disabled.
    >> To fix that, instead of a TIF flag, I am using a flag in the
    >> current->trace bitmap. I check that flag before jumping to the tracing
    >> function. That reduces the latency from 83 ns/call to 74 ns/call.
    > 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.

     \ /
      Last update: 2012-03-30 00:47    [W:0.019 / U:10.908 seconds]
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