Add the direct-io migration parameter that tells the migration code to
use O_DIRECT when opening the migration stream file whenever possible.
This is currently only used with the fixed-ram migration that has a
clear window guaranteed to perform aligned writes.
Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
include/qemu/osdep.h | 2 ++
migration/migration-hmp-cmds.c | 11 +++++++++++
migration/options.c | 30 ++++++++++++++++++++++++++++++
qapi/migration.json | 18 +++++++++++++++---
4 files changed, 58 insertions(+), 3 deletions(-)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index c7053cdc2b..645c14a65d 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -612,6 +612,8 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len,
bool exclusive);
bool qemu_has_ofd_lock(void);
#endif
+bool qemu_has_direct_io(void);
+
#if defined(__HAIKU__) && defined(__i386__)
#define FMT_pid "%ld"
#elif defined(WIN64)
diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 99b49df5dd..77313346c2 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -392,6 +392,13 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict
*qdict)
monitor_printf(mon, "%s: %s\n",
MigrationParameter_str(MIGRATION_PARAMETER_MODE),
qapi_enum_lookup(&MigMode_lookup, params->mode));
+
+ if (params->has_direct_io) {
+ monitor_printf(mon, "%s: %s\n",
+ MigrationParameter_str(
+ MIGRATION_PARAMETER_DIRECT_IO),
+ params->direct_io ? "on" : "off");
+ }
}
qapi_free_MigrationParameters(params);
@@ -681,6 +688,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict
*qdict)
p->has_mode = true;
visit_type_MigMode(v, param, &p->mode, &err);
break;
+ case MIGRATION_PARAMETER_DIRECT_IO:
+ p->has_direct_io = true;
+ visit_type_bool(v, param, &p->direct_io, &err);
+ break;
default:
assert(0);
}
diff --git a/migration/options.c b/migration/options.c
index bfcd2d7132..b347dbc670 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -823,6 +823,22 @@ int migrate_decompress_threads(void)
return s->parameters.decompress_threads;
}
+bool migrate_direct_io(void)
+{
+ MigrationState *s = migrate_get_current();
+
+ /* For now O_DIRECT is only supported with fixed-ram */
+ if (!s->capabilities[MIGRATION_CAPABILITY_FIXED_RAM]) {
+ return false;
+ }
+
+ if (s->parameters.has_direct_io) {
+ return s->parameters.direct_io;
+ }
+
+ return false;
+}
+
uint64_t migrate_downtime_limit(void)
{
MigrationState *s = migrate_get_current();
@@ -1042,6 +1058,11 @@ MigrationParameters *qmp_query_migrate_parameters(Error
**errp)
params->has_mode = true;
params->mode = s->parameters.mode;
+ if (s->parameters.has_direct_io) {
+ params->has_direct_io = true;
+ params->direct_io = s->parameters.direct_io;
+ }
+
return params;
}
@@ -1077,6 +1098,7 @@ void migrate_params_init(MigrationParameters *params)
params->has_x_vcpu_dirty_limit_period = true;
params->has_vcpu_dirty_limit = true;
params->has_mode = true;
+ params->has_direct_io = qemu_has_direct_io();
}
/*
@@ -1386,6 +1408,10 @@ static void
migrate_params_test_apply(MigrateSetParameters *params,
if (params->has_mode) {
dest->mode = params->mode;
}
+
+ if (params->has_direct_io) {
+ dest->direct_io = params->direct_io;
+ }
}
static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1530,6 +1556,10 @@ static void migrate_params_apply(MigrateSetParameters
*params, Error **errp)
if (params->has_mode) {
s->parameters.mode = params->mode;
}
+
+ if (params->has_direct_io) {
+ s->parameters.direct_io = params->direct_io;
+ }
}
void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
diff --git a/qapi/migration.json b/qapi/migration.json
index 3fce5fe53e..41241a2178 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -878,6 +878,9 @@
# @mode: Migration mode. See description in @MigMode. Default is 'normal'.
# (Since 8.2)
#
+# @direct-io: Open migration files with O_DIRECT when possible. This
+# requires that the 'fixed-ram' capability is enabled. (since 9.0)
+#
# Features:
#
# @deprecated: Member @block-incremental is deprecated. Use
@@ -911,7 +914,8 @@
'block-bitmap-mapping',
{ 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
'vcpu-dirty-limit',
- 'mode'] }
+ 'mode',
+ 'direct-io'] }
##
# @MigrateSetParameters:
@@ -1070,6 +1074,9 @@
# @mode: Migration mode. See description in @MigMode. Default is 'normal'.
# (Since 8.2)
#
+# @direct-io: Open migration files with O_DIRECT when possible. This
+# requires that the 'fixed-ram' capability is enabled. (since 9.0)
+#
# Features:
#
# @deprecated: Member @block-incremental is deprecated. Use
@@ -1123,7 +1130,8 @@
'*x-vcpu-dirty-limit-period': { 'type': 'uint64',
'features': [ 'unstable' ] },
'*vcpu-dirty-limit': 'uint64',
- '*mode': 'MigMode'} }
+ '*mode': 'MigMode',
+ '*direct-io': 'bool' } }
##
# @migrate-set-parameters:
@@ -1298,6 +1306,9 @@
# @mode: Migration mode. See description in @MigMode. Default is 'normal'.
# (Since 8.2)
#
+# @direct-io: Open migration files with O_DIRECT when possible. This
+# requires that the 'fixed-ram' capability is enabled. (since 9.0)
+#
# Features:
#
# @deprecated: Member @block-incremental is deprecated. Use
@@ -1348,7 +1359,8 @@
'*x-vcpu-dirty-limit-period': { 'type': 'uint64',
'features': [ 'unstable' ] },
'*vcpu-dirty-limit': 'uint64',
- '*mode': 'MigMode'} }
+ '*mode': 'MigMode',
+ '*direct-io': 'bool' } }
##
# @query-migrate-parameters:
--
2.35.3
