linux-kernel - [PATCH 2/5] trace-cmd: Use tracing directory to count CPUs

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Date:	Wed, 22 Aug 2012 17:43:12 +0900
From:	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Amit Shah <amit.shah@...hat.com>,
	Anthony Liguori <anthony@...emonkey.ws>,
	Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...64.org>,
	"Franch Ch. Eigler" <fche@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Ingo Molnar <mingo@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org, qemu-devel@...gnu.org,
	yrl.pp-manager.tt@...achi.com,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
Subject: [PATCH 2/5] trace-cmd: Use tracing directory to count CPUs

From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

Count debugfs/tracing/per_cpu/cpu* to determine the
number of CPUs.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
---

 trace-record.c |   41 +++++++++++++++++++++++++++++++++++++++++
 1 files changed, 41 insertions(+), 0 deletions(-)

diff --git a/trace-record.c b/trace-record.c
index 9dc18a9..ed18951 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -1179,6 +1179,41 @@ static void expand_event_list(void)
 	}
 }
 
+static int count_tracingdir_cpus(void)
+{
+	char *tracing_dir = NULL;
+	char *percpu_dir = NULL;
+	struct dirent **namelist;
+	int count = 0, n;
+
+	/* Count cpus in per_cpu directory */
+	tracing_dir = tracecmd_find_tracing_dir();
+	if (!tracing_dir)
+		return 0;
+	percpu_dir = malloc_or_die(strlen(tracing_dir) + 9);
+	if (!percpu_dir)
+		goto err;
+
+	sprintf(percpu_dir, "%s/per_cpu", tracing_dir);
+
+	n = scandir(percpu_dir, &namelist, NULL, alphasort);
+	if (n > 0) {
+		while (n--) {
+			if (strncmp("cpu", namelist[n]->d_name, 3) == 0)
+				count++;
+			free(namelist[n]);
+		}
+		free(namelist);
+	}
+
+	if (percpu_dir)
+		free(percpu_dir);
+err:
+	if (tracing_dir)
+		free(tracing_dir);
+	return count;
+}
+
 static int count_cpus(void)
 {
 	FILE *fp;
@@ -1189,6 +1224,12 @@ static int count_cpus(void)
 	size_t n;
 	int r;
 
+	cpus = count_tracingdir_cpus();
+	if (cpus > 0)
+		return cpus;
+
+	warning("failed to use tracing_dir to determine number of CPUS");
+
 	cpus = sysconf(_SC_NPROCESSORS_CONF);
 	if (cpus > 0)
 		return cpus;


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