Re: [PATCH V2 6/7] perf, x86: Use LBR call stack to get usercallchain

[Andi Kleen]

On Wed, Oct 24, 2012 at 02:21:43PM +0200, Stephane Eranian wrote:
> But still, if I do:
> $  perf record -g -e cpu/cycles/k ........
> 
> Looks like your code will activate LBR cstack for user stack even
> though I don't use it.
> I know it won't generate any user samples (theoretically) but you are
> still commandeering
> the LBR resource which other events may want to use.

You can disable it in sysfs. LBR is a power user feature and they will
know how to do this.

See it as a "prefer the needs of the 95+% over the needs of the few" default

-Andi
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