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From: Slavomir Kaslev <kaslevs@vmware.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v15 10/13] trace-cmd: Try to autodetect number of guest CPUs in setup-guest if not specified
Date: Tue,  8 Oct 2019 11:15:34 +0300
Message-ID: <20191008081537.11536-11-kaslevs@vmware.com> (raw)
In-Reply-To: <20191008081537.11536-1-kaslevs@vmware.com>

When no number of guest CPUs is provided with the -c flag to `trace-cmd
setup-guest`, try to autodetect it using virsh for libvirt managed guests.

Signed-off-by: Slavomir Kaslev <kaslevs@vmware.com>
---
 tracecmd/trace-setup-guest.c | 21 +++++++++++++++++++++
 tracecmd/trace-usage.c       |  2 +-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/tracecmd/trace-setup-guest.c b/tracecmd/trace-setup-guest.c
index 2f8bfeb..0610104 100644
--- a/tracecmd/trace-setup-guest.c
+++ b/tracecmd/trace-setup-guest.c
@@ -93,6 +93,24 @@ static int make_guest_fifos(const char *guest, int nr_cpus, mode_t mode)
 	return ret;
 }
 
+static int get_guest_cpu_count(const char *guest)
+{
+	const char *cmd_fmt = "virsh vcpucount --maximum '%s' 2>/dev/null";
+	int nr_cpus = -1;
+	char cmd[1024];
+	FILE *f;
+
+	snprintf(cmd, sizeof(cmd), cmd_fmt, guest);
+	f = popen(cmd, "r");
+	if (!f)
+		return -errno;
+
+	fscanf(f, "%d", &nr_cpus);
+	pclose(f);
+
+	return nr_cpus;
+}
+
 static void do_setup_guest(const char *guest, int nr_cpus, mode_t mode, gid_t gid)
 {
 	gid_t save_egid;
@@ -171,6 +189,9 @@ void trace_setup_guest(int argc, char **argv)
 
 	guest = argv[optind+1];
 
+	if (nr_cpus <= 0)
+		nr_cpus = get_guest_cpu_count(guest);
+
 	if (nr_cpus <= 0)
 		die("invalid number of cpus for guest %s", guest);
 
diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
index edc4ac6..b41d7d5 100644
--- a/tracecmd/trace-usage.c
+++ b/tracecmd/trace-usage.c
@@ -253,7 +253,7 @@ static struct usage_help usage_help[] = {
 	{
 		"setup-guest",
 		"create FIFOs for tracing guest VMs",
-		" %s setup-guest -c cpus[-p perm][-g group] guest\n"
+		" %s setup-guest [-c cpus][-p perm][-g group] guest\n"
 		"          -c number of guest virtual CPUs\n"
 		"          -p FIFOs permissions (default: 0660)\n"
 		"          -g FIFOs group owner\n"
-- 
2.20.1


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-08  8:15 [PATCH v15 00/13] Add VM kernel tracing over vsockets and FIFOs Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 01/13] trace-cmd: Make ports unsigned int Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 02/13] trace-cmd: Detect if vsockets are available Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 03/13] trace-cmd: Add tracecmd_create_recorder_virt() function Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 04/13] trace-cmd: Add VM tracing protocol messages Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 05/13] trace-cmd: Add buffer instance flags for tracing in guest and agent context Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 06/13] trace-cmd: Add VM kernel tracing over vsockets transport Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 07/13] trace-cmd: Use splice(2) for vsockets if available Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 08/13] trace-cmd: Switch stop recording signal to SIGUSR1 Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 09/13] trace-cmd: Add `trace-cmd setup-guest` command Slavomir Kaslev
2019-10-08  8:15 ` Slavomir Kaslev [this message]
2019-10-08  8:15 ` [PATCH v15 11/13] trace-cmd: Add setup-guest flag for attaching FIFOs to the guest VM config Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 12/13] trace-cmd: Add VM kernel tracing over FIFO transport Slavomir Kaslev
2019-10-08  8:15 ` [PATCH v15 13/13] trace-cmd: Add support for tracing VMware Workstation VMs by name Slavomir Kaslev

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