[Qemu-devel] [PATCH 09/10] Exit loop if we have been there too long

[Juan Quintela]

From: Juan Quintela <quint...@trasno.org>

cheking each 64 pages is a random magic number as good as any other.
We don't want to test too many times, but on the other hand,
qemu_get_clock_ns() is not so expensive either.

Signed-off-by: Juan Quintela <quint...@trasno.org>
Signed-off-by: Juan Quintela <quint...@redhat.com>
---
 arch_init.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index d32aaae..b463798 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -40,6 +40,7 @@
 #include "net.h"
 #include "gdbstub.h"
 #include "hw/smbios.h"
+#include "buffered_file.h"

 #ifdef TARGET_SPARC
 int graphic_width = 1024;
@@ -218,6 +219,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
     uint64_t bytes_transferred_last;
     uint64_t t0;
     double bwidth = 0;
+    int i;

     if (stage < 0) {
         cpu_physical_memory_set_dirty_tracking(0);
@@ -261,6 +263,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
     bytes_transferred_last = bytes_transferred;
     t0 = qemu_get_clock_ns(rt_clock);

+    i = 0;
     while (!qemu_file_rate_limit(f)) {
         int bytes_sent;

@@ -269,6 +272,19 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
         if (bytes_sent == 0) { /* no more blocks */
             break;
         }
+       /* we want to check in the 1st loop, just in case it was the 1st time
+           and we had to sync the dirty bitmap.
+           qemu_get_clock_ns() is a bit expensive, so we only check each some
+           iterations
+       */
+        if ((i & 63) == 0) {
+            uint64_t t1 = (qemu_get_clock_ns(rt_clock) - t0) / 1000000;
+            if (t1 > buffered_file_interval/2) {
+                printf("big delay %ld milliseconds, %d iterations\n", t1, i);
+               break;
+           }
+       }
+        i++;
     }

     t0 = qemu_get_clock_ns(rt_clock) - t0;
-- 
1.7.3.2