@@ -328,6 +328,25 @@ int libxl__save_emulator_xenstore_data(libxl__domain_save_state *dss,
return rc;
}
+/*
+ * This is the live migration precopy policy - it's called periodically during
+ * the precopy phase of live migrations, and is responsible for deciding when
+ * the precopy phase should terminate and what should be done next.
+ *
+ * The policy implemented here behaves identically to the policy previously
+ * hard-coded into xc_domain_save() - it proceeds to the stop-and-copy phase of
+ * the live migration when there are either fewer than 50 dirty pages, or more
+ * than 5 precopy rounds have completed.
+ */
+static int libxl__save_live_migration_simple_precopy_policy(
+ struct precopy_stats stats, void *user)
+{
+ return ((stats.dirty_count >= 0 && stats.dirty_count < 50) ||
+ stats.iteration >= 5)
+ ? XGS_POLICY_STOP_AND_COPY
+ : XGS_POLICY_CONTINUE_PRECOPY;
+}
+
/*----- main code for saving, in order of execution -----*/
void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss)
@@ -401,6 +420,7 @@ void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss)
if (dss->checkpointed_stream == LIBXL_CHECKPOINTED_STREAM_NONE)
callbacks->suspend = libxl__domain_suspend_callback;
+ callbacks->precopy_policy = libxl__save_live_migration_simple_precopy_policy;
callbacks->switch_qemu_logdirty = libxl__domain_suspend_common_switch_qemu_logdirty;
dss->sws.ao = dss->ao;
@@ -33,6 +33,7 @@ our @msgs = (
'xen_pfn_t', 'console_gfn'] ],
[ 9, 'srW', "complete", [qw(int retval
int errnoval)] ],
+ [ 10, 'scxW', "precopy_policy", ['struct precopy_stats', 'stats'] ]
);
#----------------------------------------
@@ -141,7 +142,8 @@ static void bytes_put(unsigned char *const buf, int *len,
END
-foreach my $simpletype (qw(int uint16_t uint32_t unsigned), 'unsigned long', 'xen_pfn_t') {
+foreach my $simpletype (qw(int uint16_t uint32_t unsigned),
+ 'unsigned long', 'xen_pfn_t', 'struct precopy_stats') {
my $typeid = typeid($simpletype);
$out_body{'callout'} .= <<END;
static int ${typeid}_get(const unsigned char **msg,
Provide an implementation of the old policy as a callback in libxl and plumb it through the IPC machinery to libxc. This serves as an example for defining a libxl policy, and provides no advantage over the default policy in libxc. Signed-off-by: Joshua Otto <jtotto@uwaterloo.ca> --- I have included this patch, as rfc, as requested by Ian, to show how libxl can provide a migration precopy policy. This was part of the same larger patch from Joshua - I have not changed or tested it. tools/libxl/libxl_dom_save.c | 20 ++++++++++++++++++++ tools/libxl/libxl_save_msgs_gen.pl | 4 +++- 2 files changed, 23 insertions(+), 1 deletion(-)