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 mapped-ram migration that has a
clear window guaranteed to perform aligned writes.
Acked-by: Markus Armbruster <arm...@redhat.com>
Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
include/qemu/osdep.h | 2 ++
migration/migration-hmp-cmds.c | 11 +++++++++++
migration/options.c | 30 ++++++++++++++++++++++++++++++
migration/options.h | 1 +
qapi/migration.json | 18 +++++++++++++++---
util/osdep.c | 9 +++++++++
6 files changed, 68 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 7e96ae6ffd..8496a2b34e 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -397,6 +397,13 @@ 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);
@@ -690,6 +697,10 @@ 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 239f5ecfb4..ae464aa4f2 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -826,6 +826,22 @@ 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 mapped-ram */
+ if (!s->capabilities[MIGRATION_CAPABILITY_MAPPED_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();
@@ -1061,6 +1077,11 @@ MigrationParameters *qmp_query_migrate_parameters(Error
**errp)
params->has_zero_page_detection = true;
params->zero_page_detection = s->parameters.zero_page_detection;
+ if (s->parameters.has_direct_io) {
+ params->has_direct_io = true;
+ params->direct_io = s->parameters.direct_io;
+ }
+
return params;
}
@@ -1097,6 +1118,7 @@ void migrate_params_init(MigrationParameters *params)
params->has_vcpu_dirty_limit = true;
params->has_mode = true;
params->has_zero_page_detection = true;
+ params->has_direct_io = qemu_has_direct_io();
}
/*
@@ -1416,6 +1438,10 @@ static void
migrate_params_test_apply(MigrateSetParameters *params,
if (params->has_zero_page_detection) {
dest->zero_page_detection = params->zero_page_detection;
}
+
+ if (params->has_direct_io) {
+ dest->direct_io = params->direct_io;
+ }
}
static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1570,6 +1596,10 @@ static void migrate_params_apply(MigrateSetParameters
*params, Error **errp)
if (params->has_zero_page_detection) {
s->parameters.zero_page_detection = params->zero_page_detection;
}
+
+ if (params->has_direct_io) {
+ s->parameters.direct_io = params->direct_io;
+ }
}
void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
diff --git a/migration/options.h b/migration/options.h
index ab8199e207..aa5509cd2a 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -76,6 +76,7 @@ uint8_t migrate_cpu_throttle_increment(void);
uint8_t migrate_cpu_throttle_initial(void);
bool migrate_cpu_throttle_tailslow(void);
int migrate_decompress_threads(void);
+bool migrate_direct_io(void);
uint64_t migrate_downtime_limit(void);
uint8_t migrate_max_cpu_throttle(void);
uint64_t migrate_max_bandwidth(void);
diff --git a/qapi/migration.json b/qapi/migration.json
index 8c65b90328..1a8a4b114c 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -914,6 +914,9 @@
# See description in @ZeroPageDetection. Default is 'multifd'.
# (since 9.0)
#
+# @direct-io: Open migration files with O_DIRECT when possible. This
+# requires that the @mapped-ram capability is enabled. (since 9.1)
+#
# Features:
#
# @deprecated: Member @block-incremental is deprecated. Use
@@ -948,7 +951,8 @@
{ 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
'vcpu-dirty-limit',
'mode',
- 'zero-page-detection'] }
+ 'zero-page-detection',
+ 'direct-io'] }
##
# @MigrateSetParameters:
@@ -1122,6 +1126,9 @@
# See description in @ZeroPageDetection. Default is 'multifd'.
# (since 9.0)
#
+# @direct-io: Open migration files with O_DIRECT when possible. This
+# requires that the @mapped-ram capability is enabled. (since 9.1)
+#
# Features:
#
# @deprecated: Member @block-incremental is deprecated. Use
@@ -1176,7 +1183,8 @@
'features': [ 'unstable' ] },
'*vcpu-dirty-limit': 'uint64',
'*mode': 'MigMode',
- '*zero-page-detection': 'ZeroPageDetection'} }
+ '*zero-page-detection': 'ZeroPageDetection',
+ '*direct-io': 'bool' } }
##
# @migrate-set-parameters:
@@ -1354,6 +1362,9 @@
# See description in @ZeroPageDetection. Default is 'multifd'.
# (since 9.0)
#
+# @direct-io: Open migration files with O_DIRECT when possible. This
+# requires that the @mapped-ram capability is enabled. (since 9.1)
+#
# Features:
#
# @deprecated: Member @block-incremental is deprecated. Use
@@ -1405,7 +1416,8 @@
'features': [ 'unstable' ] },
'*vcpu-dirty-limit': 'uint64',
'*mode': 'MigMode',
- '*zero-page-detection': 'ZeroPageDetection'} }
+ '*zero-page-detection': 'ZeroPageDetection',
+ '*direct-io': 'bool' } }
##
# @query-migrate-parameters:
diff --git a/util/osdep.c b/util/osdep.c
index e996c4744a..d0227a60ab 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -277,6 +277,15 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len,
bool exclusive)
}
#endif
+bool qemu_has_direct_io(void)
+{
+#ifdef O_DIRECT
+ return true;
+#else
+ return false;
+#endif
+}
+
static int qemu_open_cloexec(const char *name, int flags, mode_t mode)
{
int ret;
--
2.35.3
