Hi
在 08/01/2014 10:52 PM, Dr. David Alan Gilbert 写道:
* Yang Hongyang (yanghy@xxxxxxxxxxxxxx) wrote:
We need a buffer to store migration data.
On save side:
all saved data was write into colo buffer first, so that we can know
the total size of the migration data. this can also separate the data
transmission from colo control data, we use colo control data over
socket fd to synchronous both side's stat.
On restore side:
all migration data was read into colo buffer first, then load data
from the buffer: If network error happens while data transmission,
the slaver can still functinal because the migration data are not yet
loaded.
This is very similar to the QEMUSizedBuffer based QEMUFile's that Stefan Berger
wrote and that I use in both my postcopy and BER patchsets:
http://lists.gnu.org/archive/html/qemu-devel/2014-07/msg00846.html
(and to the similar code from Isaku Yamahata).
I think we should be able to use a shared version even if we need some changes.
I've being using this patch as COLO buffer, see my latest branch:
https://github.com/macrosheep/qemu/tree/colo_v0.4
But this QEMUSizedBuffer does not exactly match our needs, although it can work.
We need a static buffer that lives through COLO process so that we don't need
to alloc/free buffers every checkpoint. Currently open the buffer for write
always alloc a new buffer, I think I need the following modification:
1. ability to open an existing QEMUSizedBuffer for write
2. a reset_buf() api, that will clear buffered data, or just rewind QEMUFile
related to the buffer is enough.
Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
---
migration-colo.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)
diff --git a/migration-colo.c b/migration-colo.c
index d566b9d..b90d9b6 100644
--- a/migration-colo.c
+++ b/migration-colo.c
@@ -11,6 +11,7 @@
#include "qemu/main-loop.h"
#include "qemu/thread.h"
#include "block/coroutine.h"
+#include "qemu/error-report.h"
#include "migration/migration-colo.h"
static QEMUBH *colo_bh;
@@ -20,14 +21,122 @@ bool colo_supported(void)
return true;
}
+/* colo buffer */
+
+#define COLO_BUFFER_BASE_SIZE (1000*1000*4ULL)
+#define COLO_BUFFER_MAX_SIZE (1000*1000*1000*10ULL)
Powers of 2 are nicer!
Dave
--
Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
.
--
Thanks,
Yang.
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