2023-05-13 07:44:20

by Changbin Du

Subject: [PATCH] perf: ftrace: flush output after each writing

The pager will result stdout in full buffering mode instead of line
buffering. We need to make the trace visible timely.

Signed-off-by: Changbin Du <[email protected]>
---
tools/perf/builtin-ftrace.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 810e3376c7d6..ad2a9ae041f6 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -650,6 +650,8 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
break;
if (fwrite(buf, n, 1, stdout) != 1)
break;
+ /* flush output since stdout is in full buffering mode due to pager */
+ fflush(stdout);
}
}

--
2.25.1

2023-05-15 21:59:20

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH] perf: ftrace: flush output after each writing

Em Sat, May 13, 2023 at 03:40:00PM +0800, Changbin Du escreveu:
> The pager will result stdout in full buffering mode instead of line
> buffering. We need to make the trace visible timely.

Thanks, applied.

- Arnaldo


> Signed-off-by: Changbin Du <[email protected]>
> ---
> tools/perf/builtin-ftrace.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 810e3376c7d6..ad2a9ae041f6 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -650,6 +650,8 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace)
> break;
> if (fwrite(buf, n, 1, stdout) != 1)
> break;
> + /* flush output since stdout is in full buffering mode due to pager */
> + fflush(stdout);
> }
> }
>
> --
> 2.25.1
>

--

- Arnaldo