[Qemu-devel] [PATCH 2/7] Add tracepoints for savevm section start/end

[Juan Quintela]

This allows to know how long each section takes to save.

An awk script like this tells us sections that takes more that 10ms

$1 ~ /savevm_state_iterate_end/ {
        /* Print savevm_section_end line when > 10ms duration */
        if ($2 > 10000) {
                printf("%s times_missing=%u\n", $0, times_missing++);
        }
}

Signed-off-by: Juan Quintela <quint...@redhat.com>
---
 savevm.c     |    8 ++++++++
 trace-events |    6 ++++++
 2 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/savevm.c b/savevm.c
index 2d18bab..779bd22 100644
--- a/savevm.c
+++ b/savevm.c
@@ -85,6 +85,7 @@
 #include "cpus.h"
 #include "memory.h"
 #include "qmp-commands.h"
+#include "trace.h"

 #define SELF_ANNOUNCE_ROUNDS 5

@@ -1624,11 +1625,14 @@ int qemu_savevm_state_iterate(QEMUFile *f)
         if (se->save_live_state == NULL)
             continue;

+        trace_savevm_section_start();
         /* Section type */
         qemu_put_byte(f, QEMU_VM_SECTION_PART);
         qemu_put_be32(f, se->section_id);

         ret = se->save_live_state(f, QEMU_VM_SECTION_PART, se->opaque);
+        trace_savevm_section_end(se->section_id);
+
         if (ret <= 0) {
             /* Do not proceed to the next vmstate before this one reported
                completion of the current stage. This serializes the migration
@@ -1658,11 +1662,13 @@ int qemu_savevm_state_complete(QEMUFile *f)
         if (se->save_live_state == NULL)
             continue;

+        trace_savevm_section_start();
         /* Section type */
         qemu_put_byte(f, QEMU_VM_SECTION_END);
         qemu_put_be32(f, se->section_id);

         ret = se->save_live_state(f, QEMU_VM_SECTION_END, se->opaque);
+        trace_savevm_section_end(se->section_id);
         if (ret < 0) {
             return ret;
         }
@@ -1674,6 +1680,7 @@ int qemu_savevm_state_complete(QEMUFile *f)
        if (se->save_state == NULL && se->vmsd == NULL)
            continue;

+        trace_savevm_section_start();
         /* Section type */
         qemu_put_byte(f, QEMU_VM_SECTION_FULL);
         qemu_put_be32(f, se->section_id);
@@ -1687,6 +1694,7 @@ int qemu_savevm_state_complete(QEMUFile *f)
         qemu_put_be32(f, se->version_id);

         vmstate_save(f, se);
+        trace_savevm_section_end(se->section_id);
     }

     qemu_put_byte(f, QEMU_VM_EOF);
diff --git a/trace-events b/trace-events
index 87cb96c..73d5f81 100644
--- a/trace-events
+++ b/trace-events
@@ -741,6 +741,11 @@ displaysurface_resize(void *display_state, void 
*display_surface, int width, int
 # vga.c
 ppm_save(const char *filename, void *display_surface) "%s surface=%p"

+# savevm.c
+
+savevm_section_start(void) ""
+savevm_section_end(unsigned int section_id) "section_id %u"
+
 # hw/qxl.c
 disable qxl_interface_set_mm_time(int qid, uint32_t mm_time) "%d %d"
 disable qxl_io_write_vga(int qid, const char *mode, uint32_t addr, uint32_t 
val) "%d %s addr=%u val=%u"
@@ -805,3 +810,4 @@ qxl_render_blit_guest_primary_initialized(void) ""
 qxl_render_blit(int32_t stride, int32_t left, int32_t right, int32_t top, 
int32_t bottom) "stride=%d [%d, %d, %d, %d]"
 qxl_render_guest_primary_resized(int32_t width, int32_t height, int32_t 
stride, int32_t bytes_pp, int32_t bits_pp) "%dx%d, stride %d, bpp %d, depth %d"
 qxl_render_update_area_done(void *cookie) "%p"
+
-- 
1.7.7.6