linux-kernel - Re: [PATCH] perf tools: intel-pt: fix endless record after being terminated

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Message-ID: <539e4aca-3bae-6586-fefd-8be49308b5d7@intel.com>
Date:   Mon, 13 Jan 2020 16:47:18 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Wei Li <liwei391@...wei.com>, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org
Cc:     peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, huawei.libin@...wei.com
Subject: Re: [PATCH] perf tools: intel-pt: fix endless record after being
 terminated

On 2/01/20 9:42 am, Wei Li wrote:
> In __cmd_record(), when receiving SIGINT(ctrl + c), a done flag will
> be set and the event list will be disabled by evlist__disable() once.
> 
> While in auxtrace_record.read_finish(), the related events will be
> enabled again, if they are continuous, the recording seems to be endless.
> 
> If the intel_pt event is disabled, we don't enable it again here.
> 
> Before the patch:
> huawei@...wei-2288H-V5:~/linux-5.5-rc4/tools/perf$ ./perf record -e \
> intel_pt//u -p 46803
> ^C^C^C^C^C^C
> 
> After the patch:
> huawei@...wei-2288H-V5:~/linux-5.5-rc4/tools/perf$ ./perf record -e \
> intel_pt//u -p 48591
> ^C[ perf record: Woken up 0 times to write data ]
> Warning:
> AUX data lost 504 times out of 4816!
> 
> [ perf record: Captured and wrote 2024.405 MB perf.data ]
> 
> Signed-off-by: Wei Li <liwei391@...wei.com>

All ->read_finish() implementations seem the same, so can we make a common
helper auxtrace_read_finish() and set all .read_finish = to that.

> ---
>  tools/perf/arch/x86/util/intel-pt.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
> index 20df442fdf36..1e96afcd8646 100644
> --- a/tools/perf/arch/x86/util/intel-pt.c
> +++ b/tools/perf/arch/x86/util/intel-pt.c
> @@ -1173,9 +1173,13 @@ static int intel_pt_read_finish(struct auxtrace_record *itr, int idx)
>  	struct evsel *evsel;
>  
>  	evlist__for_each_entry(ptr->evlist, evsel) {
> -		if (evsel->core.attr.type == ptr->intel_pt_pmu->type)
> -			return perf_evlist__enable_event_idx(ptr->evlist, evsel,
> -							     idx);
> +		if (evsel->core.attr.type == ptr->intel_pt_pmu->type) {
> +			if (evsel->disabled)
> +				return 0;
> +			else
> +				return perf_evlist__enable_event_idx(
> +						ptr->evlist, evsel, idx);
> +		}
>  	}
>  	return -EINVAL;
>  }
>