Messages in this thread | | | From | Vince Weaver <> | Date | Mon, 2 Mar 2015 16:19:15 -0500 (EST) | Subject | Re: [patch] perf_event_open.2: 3.19 PERF_SAMPLE_REGS_INTR support |
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On Mon, 2 Mar 2015, Stephane Eranian wrote:
> vince,
> PEBS machine state. Problem is that there is only one set of pt_regs passed to > __intel_pmu_pebs_event(). And if REGS_INTR is set, then the pt_regs > registers are > indeed overwritten with PEBS captured state. To avoid the issue, we > would have to > carry around two sets of pt_regs.
I don't think we have to carry around both (would that ever be useful?) Just that the behavior is a bit surprising and I should document it in the manpage.
One question I do have: if it never makes sense to measure REGS_USER and REGS_INTR at the same time, why was the latter added at all? Why not just have the REGS_USER information automatically upgrade to REGS_INTR if precise_ip is high enough?
Vince
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