[Qemu-devel] [PATCH v1] trace: add qemu_system_powerdown_request and qemu_system_shutdown_request trace events

[Yang Zhiyong <yangzy.fnst@cn.fujitsu.com>]

We have the experience that the guest doesn't stop successfully 
though it was instructed to shut down.

The root cause may be not in QEMU mostly.  However, QEMU is often
suspected at the beginning just because the issue occurred in
virtualization environment.

Therefore, we need to affirm that QEMU received the shutdown  
request and raised ACPI irq from "virsh shutdown" command, 
virt-manger or stopping QEMU process to the VM .
So that we can affirm the problems was belonged to the Guset OS 
rather than the QEMU itself.

When we stop guests by "virsh shutdown" command or virt-manger, 
or stopping QEMU process，qemu_system_powerdown_request() or
qemu_system_shutdown_request() is called. Then the below functions 
in main_loop_should_exit() of Vl.c are called roughly in the 
following order.
	
	if (qemu_powerdown_requested()) 
		qemu_system_powerdown()
			monitor_protocol_event(QEVENT_POWERDOWN, NULL)
		
	OR
	
	if(qemu_shutdown_requested()} 
		monitor_protocol_event(QEVENT_SHUTDOWN, NULL);

The tracepoint of monitor_protocol_event() already exists, but no
tracepoints are defined for qemu_system_powerdown_request() and 
qemu_system_shutdown_request(). So this patch adds two tracepoints for 
the two functions. We believe that it will become much easier to 
isolate the problem mentioned above by these tracepoints.


Signed-off-by: Yang Zhiyong <yangzy.fnst@cn.fujitsu.com>

---
 trace-events |    2 ++
 vl.c         |    2 ++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/trace-events b/trace-events
index 2c5b307..d642cc4 100644
--- a/trace-events
+++ b/trace-events
@@ -511,6 +511,8 @@ g_malloc(size_t size, void *ptr) "size %zu ptr %p"
 g_realloc(void *ptr, size_t size, void *newptr) "ptr %p size %zu newptr %p"
 g_free(void *ptr) "ptr %p"
 system_wakeup_request(int reason) "reason=%d"
+qemu_system_shutdown_request(void) ""
+qemu_system_powerdown_request(void) ""
 
 # block/qcow2.c
 qcow2_writev_start_req(void *co, int64_t sector, int nb_sectors) "co %p sector %" PRIx64 " nb_sectors %d"
diff --git a/vl.c b/vl.c
index 709d8cd..aed0868 100644
--- a/vl.c
+++ b/vl.c
@@ -1982,6 +1982,7 @@ void qemu_system_killed(int signal, pid_t pid)
 
 void qemu_system_shutdown_request(void)
 {
+    trace_qemu_system_shutdown_request();
     shutdown_requested = 1;
     qemu_notify_event();
 }
@@ -1994,6 +1995,7 @@ static void qemu_system_powerdown(void)
 
 void qemu_system_powerdown_request(void)
 {
+    trace_qemu_system_powerdown_request();
     powerdown_requested = 1;
     qemu_notify_event();
 }
-- 
1.7.1