Re: [PATCH] perf hist: Fix branch_info index for sample weight

[James Clark]

On 04/11/2026 09:02, Gu Bin wrote:
> iter_add_next_branch_entry() is called once per branch and uses &bi[i]
> for the hist entry, but reads the weight from bi->flags.cycles (i.e.
> bi[0]) for every branch, so every entry is weighted with the first
> branch's cycle count. This is incorrect when the branch stack contains
> more than one entry with different cycle counts, as the weight of each
> hist entry fails to reflect the cycles of its own branch.
>
> Use bi[i].flags.cycles, as the surrounding code already does.
>
> Fixes: 0e332f033a82 ("perf tools: Add support for cycles, weight branch_info field")
> Signed-off-by: Gu Bin <gubin@xxxxxxxxxxxxxxxxxxxx>
> ---
>   tools/perf/util/hist.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> index e75a4fcce975..364754e9d12a 100644
> --- a/tools/perf/util/hist.c
> +++ b/tools/perf/util/hist.c
> @@ -1055,7 +1055,7 @@ iter_add_next_branch_entry(struct hist_entry_iter *iter, struct addr_location *a
>   	 * and not events sampled. Thus we use a pseudo period of 1.
>   	 */
>   	sample->period = 1;
> -	sample->weight = bi->flags.cycles ? bi->flags.cycles : 1;
> +	sample->weight = bi[i].flags.cycles ? bi[i].flags.cycles : 1;
>   
>   	he = hists__add_entry(hists, al, iter->parent, &bi[i], NULL, NULL,
>   			      sample, true);

Reviewed-by: James Clark <james.clark@xxxxxxxxxx>