linux-kernel - [PATCHv3 6/7] perf record: Use perf_data_file_

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Date:	Thu, 28 Nov 2013 16:21:37 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mike Galbraith <efault@....de>,
	David Ahern <dsahern@...il.com>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCHv3 6/7] perf record: Use perf_data_file__write for output file

On Thu, Nov 28, 2013 at 12:03:44PM -0200, Arnaldo Carvalho de Melo wrote:
> Em Thu, Nov 28, 2013 at 11:30:18AM +0100, Jiri Olsa escreveu:
> > Changing the file output code to use the newly
> > added perf_data_file__write interface.
> > 
> > No functional change intended.
> 
> But there is one, if we fail the pr_err() will not be called, will some
> warning be emitter later on?

ouch right, I missed that one... attached v3 ;-)

> 
> If so, we should make it clear in the changelog. Lemme check by looking
> at that code...

I think it's better we dont change the functionality,
just factor the code..

> 
> There are several places where the return of this function is propagated
> and handled with relevant error messages, but at least one, the most
> important, doesn't, i.e. this would be the only message the user would
> receive, can you verify that?

AFAICS they print out high(er) level errors, like for sythesizing
events:
                pr_err("Couldn't record guest kernel [%d]'s reference"
                       " relocation symbol.\n", machine->pid);

I think we want that write failure message as well

thanks,
jirka


---
Changing the file output code to use the newly
added perf_data_file__write interface.

No functional change intended.

Signed-off-by: Jiri Olsa <jolsa@...hat.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Mike Galbraith <efault@....de>
Cc: David Ahern <dsahern@...il.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-record.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index d93e2ee..2402eff 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -76,24 +76,19 @@ struct perf_record {
 	long			samples;
 };
 
-static int perf_record__write(struct perf_record *rec, void *buf, size_t size)
+static ssize_t perf_record__write(struct perf_record *rec,
+				  void *buf, size_t size)
 {
-	struct perf_data_file *file = &rec->file;
-
-	while (size) {
-		ssize_t ret = write(file->fd, buf, size);
-
-		if (ret < 0) {
-			pr_err("failed to write perf data, error: %m\n");
-			return -1;
-		}
-
-		size -= ret;
-		buf += ret;
+	struct perf_session *session = rec->session;
+	ssize_t ret;
 
-		rec->bytes_written += ret;
+	ret = perf_data_file__write(session->file, buf, size);
+	if (ret < 0) {
+		pr_err("failed to write perf data, error: %m\n");
+		return -1;
 	}
 
+	rec->bytes_written += ret;
 	return 0;
 }
 
-- 
1.8.3.1

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