Re: [PATCH v3 4/4] hwtracing: hisi_ptt: Advertise PERF_PMU_CAP_NO_EXCLUDE for PTT PMU

[Jonathan Cameron]

On Tue, 23 May 2023 17:32:28 +0800
Yicong Yang <yangyicong@xxxxxxxxxx> wrote:

> From: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
> 
> The PTT trace collects PCIe TLP headers from the PCIe link and don't
> have the ability to exclude certain context. It doesn't support itrace
> as well. So only advertise PERF_PMU_CAP_NO_EXCLUDE. This will greatly
> save the storage of final data. Tested tracing idle link for ~15s,
> without this patch we'll collect ~28.682MB data for context related
> information and with this patch it reduced to ~0.226MB.
> 
> Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Interesting - I didn't know about this flag.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

> ---
>  drivers/hwtracing/ptt/hisi_ptt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
> index 65f4288a1915..b9917db849bf 100644
> --- a/drivers/hwtracing/ptt/hisi_ptt.c
> +++ b/drivers/hwtracing/ptt/hisi_ptt.c
> @@ -1210,7 +1210,7 @@ static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
>  
>  	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
>  		.module		= THIS_MODULE,
> -		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
> +		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
>  		.task_ctx_nr	= perf_sw_context,
>  		.attr_groups	= hisi_ptt_pmu_groups,
>  		.event_init	= hisi_ptt_pmu_event_init,