linux-kernel - Re: [PATCH 4/4] hwtracing: hisi_ptt: Advertise PERF_PMU_CAP_NO

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Date:   Tue, 28 Mar 2023 17:53:16 +0100
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Yicong Yang <yangyicong@...wei.com>
CC:     <mathieu.poirier@...aro.org>, <suzuki.poulose@....com>,
        <corbet@....net>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <alexander.shishkin@...ux.intel.com>,
        <helgaas@...nel.org>, <linux-pci@...r.kernel.org>,
        <prime.zeng@...wei.com>, <linuxarm@...wei.com>
Subject: Re: [PATCH 4/4] hwtracing: hisi_ptt: Advertise
 PERF_PMU_CAP_NO_EXCLUDE for PTT PMU

On Wed, 15 Mar 2023 17:43:16 +0800
Yicong Yang <yangyicong@...wei.com> wrote:

> From: Yicong Yang <yangyicong@...ilicon.com>
> 
> 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@...ilicon.com>

Seems reasonable.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

> ---
>  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 a5cd87edb813..8c1cce32b83f 100644
> --- a/drivers/hwtracing/ptt/hisi_ptt.c
> +++ b/drivers/hwtracing/ptt/hisi_ptt.c
> @@ -1216,7 +1216,7 @@ 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,