Re: [PATCH] perf: add support for logging debug messages to file

[Jiri Olsa <jolsa@redhat.com>]

On Sun, Sep 15, 2019 at 06:27:40PM +0800, Changbin Du wrote:
> When in TUI mode, it is impossible to show all the debug messages to
> console. This make it hard to debug perf issues using debug messages.
> This patch adds support for logging debug messages to file to resolve
> this problem.
> 
> The usage is:
> perf -debug verbose=2 --debug file=1 COMMAND
> 
> And the path of log file is '~/perf.log'.
> 
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> ---
>  tools/perf/Documentation/perf.txt |  4 +++-
>  tools/perf/util/debug.c           | 20 ++++++++++++++++++++
>  2 files changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/Documentation/perf.txt b/tools/perf/Documentation/perf.txt
> index 401f0ed67439..45db7b22d1a5 100644
> --- a/tools/perf/Documentation/perf.txt
> +++ b/tools/perf/Documentation/perf.txt
> @@ -16,7 +16,8 @@ OPTIONS
>  	Setup debug variable (see list below) in value
>  	range (0, 10). Use like:
>  	  --debug verbose   # sets verbose = 1
> -	  --debug verbose=2 # sets verbose = 2
> +	  --debug verbose=2 --debug file=1
> +	                    # sets verbose = 2 and save log to file

it's variable already, why not allow to pass the path directly like:

  --debug file=~/perf.log

would be great if we won't need to use --debug twice and allow:

  --debug verbose=2,file=perf.log

jirka