linux-kernel - Re: [PATCH v2] perf script: Update brstack syntax documentation

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Message-ID: <0259da8e-abe7-4d07-96e5-948f7685c2a1@amd.com>
Date: Fri, 14 Mar 2025 12:34:13 +0530
From: Sandipan Das <sandipan.das@....com>
To: Yujie Liu <yujie.liu@...el.com>
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 "Liang, Kan" <kan.liang@...ux.intel.com>, Andi Kleen <ak@...ux.intel.com>,
 Martin Liska <martin.liska@....com>, James Clark <james.clark@...aro.org>,
 Leo Yan <leo.yan@....com>
Subject: Re: [PATCH v2] perf script: Update brstack syntax documentation

On 3/12/2025 12:53 PM, Yujie Liu wrote:
> The following commits added new fields/flags to the branch stack field
> list:
> 
> commit 1f48989cdc7d ("perf script: Output branch sample type")
> commit 6ade6c646035 ("perf script: Show branch speculation info")
> commit 1e66dcff7b9b ("perf script: Add not taken event for branch stack")
> 
> Update brstack syntax documentation to be consistent with the latest
> branch stack field list. Improve the descriptions to help users
> interpret the fields accurately.
> 
> Signed-off-by: Yujie Liu <yujie.liu@...el.com>
> ---
> Changes in v2:
> - Add not taken event (Namhyung, Leo)
> - Change field name from PRED to EVENT for generic use and furture
>   extension (Leo)
> 
> v1: https://lore.kernel.org/all/20250225061736.1698175-1-yujie.liu@intel.com/
> ---
>  tools/perf/Documentation/perf-script.txt | 23 ++++++++++++++++-------
>  1 file changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
> index b72866ef270b..28bec7e78bc8 100644
> --- a/tools/perf/Documentation/perf-script.txt
> +++ b/tools/perf/Documentation/perf-script.txt
> @@ -239,13 +239,22 @@ OPTIONS
>  	i.e., -F "" is not allowed.
>  
>  	The brstack output includes branch related information with raw addresses using the
> -	/v/v/v/v/cycles syntax in the following order:
> -	FROM: branch source instruction
> -	TO  : branch target instruction
> -        M/P/-: M=branch target mispredicted or branch direction was mispredicted, P=target predicted or direction predicted, -=not supported
> -	X/- : X=branch inside a transactional region, -=not in transaction region or not supported
> -	A/- : A=TSX abort entry, -=not aborted region or not supported
> -	cycles
> +	FROM/TO/EVENT/INTX/ABORT/CYCLES/TYPE/SPEC syntax in the following order:
> +	FROM  : branch source instruction
> +	TO    : branch target instruction
> +	EVENT : M=branch target or direction was mispredicted
> +	        P=branch target or direction was predicted
> +	        N=branch not-taken
> +	        -=no event or not supported
> +	INTX  : X=branch inside a transactional region
> +	        -=branch not in transaction region or not supported
> +	ABORT : A=TSX abort entry
> +	        -=not aborted region or not supported
> +	CYCLES: the number of cycles that have elapsed since the last branch was recorded
> +	TYPE  : branch type: COND/UNCOND/IND/CALL/IND_CALL/RET etc.
> +	        -=not supported
> +	SPEC  : branch speculation info: SPEC_WRONG_PATH/NON_SPEC_CORRECT_PATH/SPEC_CORRECT_PATH
> +	        -=not supported
>  
>  	The brstacksym is identical to brstack, except that the FROM and TO addresses are printed in a symbolic form if possible.
>  
> 
> base-commit: b10f74308e1305275e69ddde711ec817cc69e306


Reviewed-by: Sandipan Das <sandipan.das@....com>