linux-kernel - Re: [PATCH 1/2] perf trace: Use pr_debug() instead of fprintf() for logging

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Message-ID: <20190617152412.GJ1402@kernel.org>
Date:   Mon, 17 Jun 2019 12:24:12 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH 1/2] perf trace: Use pr_debug() instead of fprintf() for
 logging

Em Mon, Jun 17, 2019 at 05:11:39PM +0800, Leo Yan escreveu:
> In the function trace__syscall_info(), it explicitly checks verbose
> level and print out log with fprintf().  Actually, we can use
> pr_debug() to do the same thing for debug logging.
> 
> This patch uses pr_debug() instead of fprintf() for debug logging; it
> includes a minor fixing for 'space before tab in indent', which
> dismisses git warning when apply it.

But those are not fprintf(stdout,), they explicitely redirect to the
output file that the user may have specified using 'perf trace --output
filename.trace' :-)

- Arnaldo
 
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
>  tools/perf/builtin-trace.c | 21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index bd1f00e7a2eb..5cd74651db4c 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1760,12 +1760,11 @@ static struct syscall *trace__syscall_info(struct trace *trace,
>  		 * grep "NR -1 " /t/trace_pipe
>  		 *
>  		 * After generating some load on the machine.
> - 		 */
> -		if (verbose > 1) {
> -			static u64 n;
> -			fprintf(trace->output, "Invalid syscall %d id, skipping (%s, %" PRIu64 ") ...\n",
> -				id, perf_evsel__name(evsel), ++n);
> -		}
> +		 */
> +		static u64 n;
> +
> +		pr_debug("Invalid syscall %d id, skipping (%s, %" PRIu64 ")\n",
> +			 id, perf_evsel__name(evsel), ++n);
>  		return NULL;
>  	}
>  
> @@ -1779,12 +1778,10 @@ static struct syscall *trace__syscall_info(struct trace *trace,
>  	return &trace->syscalls.table[id];
>  
>  out_cant_read:
> -	if (verbose > 0) {
> -		fprintf(trace->output, "Problems reading syscall %d", id);
> -		if (id <= trace->syscalls.max && trace->syscalls.table[id].name != NULL)
> -			fprintf(trace->output, "(%s)", trace->syscalls.table[id].name);
> -		fputs(" information\n", trace->output);
> -	}
> +	pr_debug("Problems reading syscall %d", id);
> +	if (id <= trace->syscalls.max && trace->syscalls.table[id].name != NULL)
> +		pr_debug("(%s)", trace->syscalls.table[id].name);
> +	pr_debug(" information\n");
>  	return NULL;
>  }
>  
> -- 
> 2.17.1

-- 

- Arnaldo