Re: [RFC 00/11] perf: Enhancing perf to export processor hazard information

[Peter Zijlstra]

On Mon, Mar 02, 2020 at 10:53:44AM +0530, Ravi Bangoria wrote:
> Modern processors export such hazard data in Performance
> Monitoring Unit (PMU) registers. Ex, 'Sampled Instruction Event
> Register' on IBM PowerPC[1][2] and 'Instruction-Based Sampling' on
> AMD[3] provides similar information.
> 
> Implementation detail:
> 
> A new sample_type called PERF_SAMPLE_PIPELINE_HAZ is introduced.
> If it's set, kernel converts arch specific hazard information
> into generic format:
> 
>   struct perf_pipeline_haz_data {
>          /* Instruction/Opcode type: Load, Store, Branch .... */
>          __u8    itype;
>          /* Instruction Cache source */
>          __u8    icache;
>          /* Instruction suffered hazard in pipeline stage */
>          __u8    hazard_stage;
>          /* Hazard reason */
>          __u8    hazard_reason;
>          /* Instruction suffered stall in pipeline stage */
>          __u8    stall_stage;
>          /* Stall reason */
>          __u8    stall_reason;
>          __u16   pad;
>   };

Kim, does this format indeed work for AMD IBS?