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[Qemu-devel] [PATCH 6/8] Exit loop if we have been there too long
From: |
Juan Quintela |
Subject: |
[Qemu-devel] [PATCH 6/8] Exit loop if we have been there too long |
Date: |
Fri, 22 Jun 2012 15:46:17 +0200 |
Checking 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. We want to be sure
that we spent less than 50ms (half of buffered_file timer), if we
spent more than 100ms, all the accounting got wrong.
Signed-off-by: Juan Quintela <address@hidden>
---
arch_init.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/arch_init.c b/arch_init.c
index 424efe7..7de1abf 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -294,12 +294,15 @@ static void sort_ram_list(void)
g_free(blocks);
}
+#define MAX_WAIT 50 /* ms, half buffered_file limit */
+
int ram_save_live(QEMUFile *f, int stage, void *opaque)
{
ram_addr_t addr;
uint64_t bytes_transferred_last;
double bwidth = 0;
int ret;
+ int i;
if (stage < 0) {
memory_global_dirty_log_stop();
@@ -339,6 +342,7 @@ int ram_save_live(QEMUFile *f, int stage, void *opaque)
bytes_transferred_last = bytes_transferred;
bwidth = qemu_get_clock_ns(rt_clock);
+ i = 0;
while ((ret = qemu_file_rate_limit(f)) == 0) {
int bytes_sent;
@@ -347,6 +351,19 @@ int ram_save_live(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) - bwidth) / 1000000;
+ if (t1 > MAX_WAIT) {
+ DPRINTF("big wait: %ld milliseconds, %d iterations\n", t1, i);
+ break;
+ }
+ }
+ i++;
}
if (ret < 0) {
--
1.7.10.2