Re: [PATCH 1/3] perf: Use sample_flags for callchain

[Liang, Kan]

On 2022-09-08 5:41 p.m., Namhyung Kim wrote:
> So that it can call perf_callchain() only if needed.  Historically it used
> __PERF_SAMPLE_CALLCHAIN_EARLY but we can do that with sample_flags in the
> struct perf_sample_data.
> 
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>

The series look good to me.

Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

Thanks,
Kan

> ---
>  arch/x86/events/amd/ibs.c  | 4 +++-
>  arch/x86/events/intel/ds.c | 8 ++++++--
>  kernel/events/core.c       | 2 +-
>  3 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
> index c251bc44c088..dab094166693 100644
> --- a/arch/x86/events/amd/ibs.c
> +++ b/arch/x86/events/amd/ibs.c
> @@ -798,8 +798,10 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
>  	 * recorded as part of interrupt regs. Thus we need to use rip from
>  	 * interrupt regs while unwinding call stack.
>  	 */
> -	if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
> +	if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
>  		data.callchain = perf_callchain(event, iregs);
> +		data.sample_flags |= PERF_SAMPLE_CALLCHAIN;
> +	}
>  
>  	throttle = perf_event_overflow(event, &data, &regs);
>  out:
> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
> index a5275c235c2a..4ba6ab6d0d92 100644
> --- a/arch/x86/events/intel/ds.c
> +++ b/arch/x86/events/intel/ds.c
> @@ -1546,8 +1546,10 @@ static void setup_pebs_fixed_sample_data(struct perf_event *event,
>  	 * previous PMI context or an (I)RET happened between the record and
>  	 * PMI.
>  	 */
> -	if (sample_type & PERF_SAMPLE_CALLCHAIN)
> +	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
>  		data->callchain = perf_callchain(event, iregs);
> +		data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
> +	}
>  
>  	/*
>  	 * We use the interrupt regs as a base because the PEBS record does not
> @@ -1719,8 +1721,10 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event,
>  	 * previous PMI context or an (I)RET happened between the record and
>  	 * PMI.
>  	 */
> -	if (sample_type & PERF_SAMPLE_CALLCHAIN)
> +	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
>  		data->callchain = perf_callchain(event, iregs);
> +		data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
> +	}
>  
>  	*regs = *iregs;
>  	/* The ip in basic is EventingIP */
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 15d27b14c827..b8af9fdbf26f 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7323,7 +7323,7 @@ void perf_prepare_sample(struct perf_event_header *header,
>  	if (sample_type & PERF_SAMPLE_CALLCHAIN) {
>  		int size = 1;
>  
> -		if (!(sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
> +		if (filtered_sample_type & PERF_SAMPLE_CALLCHAIN)
>  			data->callchain = perf_callchain(event, regs);
>  
>  		size += data->callchain->nr;