[Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 10/06/2011 03:06 PM, Steven Rostedt wrote:
> But it only speeds up the tracing case. The non-tracing case is a nop
> and 5bytes is 5bytes regardless.
>
> Did you see a 5% speed up while tracing was happening? How did you do
> your test. I find a 5 byte compared to a 2 byte jump being negligible
> with the rest of the overhead of tracing, but I could be wrong.

You're right, this was a completely artificial microbenchmark.  In
practice the improvement would be a much smaller effect.

But bear in mind, I'm not using jump-label for tracing.  While its
important for the "disabled" state to be quick, performance of the
"enabled" state is also important.

Thanks,
    J

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