On 22/08/2019 11:33, Eric Blake wrote:
On 8/21/19 8:16 PM, Alexey Kardashevskiy wrote:
This returns MD5 checksum of all RAM blocks for migration debugging
as this is way faster than saving the entire RAM to a file and checking
that.
Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
I am actually wondering if there is an easier way of getting these
checksums and I just do not see it, it cannot be that we fixed all
memory migration bugs :)
I'm not sure whether the command itself makes sense, but for the interface:
+++ b/qapi/misc.json
@@ -1194,6 +1194,33 @@
##
{ 'command': 'query-memory-size-summary', 'returns': 'MemoryInfo' }
+##
+# @MemoryChecksum:
+#
+# A string with MD5 checksum of all RAMBlocks.
+#
+# @checksum: the checksum.
+#
+# Since: 3.2.0
This should be 4.2, not 3.2.
+##
+{ 'struct': 'MemoryChecksum',
+ 'data' : { 'checksum': 'str' } }
+
+##
+# @query-memory-checksum:
+#
+# Return the MD5 checksum of all RAMBlocks.
+#
+# Example:
+#
+# -> { "execute": "query-memory-checksum" }
+# <- { "return": { "checksum": "a0880304994f64cb2edad77b9a1cd58f" } }
+#
+# Since: 3.2.0
and again
+##
+{ 'command': 'query-memory-checksum',
+ 'returns': 'MemoryChecksum' }
+
+++ b/exec.c
@@ -2050,6 +2050,22 @@ void *qemu_ram_get_host_addr(RAMBlock *rb)
return rb->host;
}
+gchar *qemu_ram_chksum(void)
gchar is a pointless glib type. Use 'char' instead.
+{
+ struct RAMBlock *rb;
+ GChecksum *chksum = g_checksum_new(G_CHECKSUM_MD5);
+ gchar *ret;
+
+ RAMBLOCK_FOREACH(rb) {
+ g_checksum_update(chksum, qemu_ram_get_host_addr(rb),
+ qemu_ram_get_used_length(rb));
+ }
+ ret = g_strdup(g_checksum_get_string(chksum));
+ g_checksum_free(chksum);
+
+ return ret;
+}
How long does this take to run? Is it something where you really want
to block the guest while chewing over the guest's entire memory?
10-20 times faster than "pmemsave" and blocking the guest is not a
problem here as both - source and destination - guests are stopped
(otherwise the checksum does not make sense).
--
Alexey