Re: [PATCH V7 11/17] perf, core: expose LBR call stack to user perf tool

From: Peter Zijlstra
Date: Wed Nov 05 2014 - 04:21:10 EST


On Tue, Nov 04, 2014 at 09:56:07PM -0500, Kan Liang wrote:
> From: Yan, Zheng <zheng.z.yan@xxxxxxxxx>

Now for this patch I'm fairly sure Zheng didn't actually write it; his
last posting did something different IIRC.

> With LBR call stack feature enable, there are two call chain data

_three_, LBR is the 3rd.

> sources, traditional frame pointer and LBR call stack.
> This patch extends the perf_callchain_entry struct to mark the available
> call chain source.
> The frame pointer is still output as PERF_SAMPLE_CALLCHAIN data format.
> The LBR call stack data will be output as PERF_SAMPLE_BRANCH_STACK data
> format.

I'm not sure what this patch does?! Why do the FP based callchains need
_any_ changes?
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