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Subject: [QEMU 3/7] Add the hmp and qmp interface for dropping cache
Add the hmp and qmp interface to drop vm's page cache, users
can control the type of cache they want vm to drop.
Signed-off-by: Liang Li <liang.z.li@intel.com>
---
balloon.c | 19 +++++++++++++++++++
hmp-commands.hx | 15 +++++++++++++++
hmp.c | 22 ++++++++++++++++++++++
hmp.h | 3 +++
monitor.c | 18 ++++++++++++++++++
qapi-schema.json | 35 +++++++++++++++++++++++++++++++++++
qmp-commands.hx | 23 +++++++++++++++++++++++
7 files changed, 135 insertions(+)
diff --git a/balloon.c b/balloon.c
index 0fb34bf..3d96111 100644
--- a/balloon.c
+++ b/balloon.c
@@ -122,3 +122,22 @@ void qmp_balloon(int64_t target, Error **errp)
trace_balloon_event(balloon_opaque, target);
balloon_event_fn(balloon_opaque, target);
}
+
+void qmp_balloon_drop_cache(DropCacheType type, Error **errp)
+{
+ if (!have_balloon(errp)) {
+ return;
+ }
+
+ if (!balloon_drop_cache_fn) {
+ error_setg(errp, QERR_UNSUPPORTED);
+ return;
+ }
+ if (type < 0 && type >= DROP_CACHE_TYPE__MAX) {
+ error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "type",
+ "a value in range[0, 3]");
+ return;
+ }
+
+ balloon_drop_cache_fn(balloon_opaque, type);
+}
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 98b4b1a..c73572c 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1378,6 +1378,21 @@ Request VM to change its memory allocation to @var{value} (in MB).
ETEXI
{
+ .name = "balloon_drop_cache",
+ .args_type = "type:s",
+ .params = "type",
+ .help = "request VM to drop its page caches",
+ .mhandler.cmd = hmp_balloon_drop_cache,
+ .command_completion = balloon_drop_cache_completion
+ },
+
+STEXI
+@item balloon_drop_cache @var{type}
+@findex balloon_drop_cache
+Request VM to dorp its page caches.
+ETEXI
+
+ {
.name = "set_link",
.args_type = "name:s,up:b",
.params = "name on|off",
diff --git a/hmp.c b/hmp.c
index a4b1d3d..3aa1062 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1061,6 +1061,28 @@ void hmp_balloon(Monitor *mon, const QDict *qdict)
}
}
+void hmp_balloon_drop_cache(Monitor *mon, const QDict *qdict)
+{
+ const char *type = qdict_get_str(qdict, "type");
+ Error *err = NULL;
+ int i;
+
+ for (i = 0; i < DROP_CACHE_TYPE__MAX; i++) {
+ if (strcmp(type, DropCacheType_lookup[i]) == 0) {
+ qmp_balloon_drop_cache(1 + i, &err);
+ break;
+ }
+ }
+
+ if (i == DROP_CACHE_TYPE__MAX) {
+ error_setg(&err, QERR_INVALID_PARAMETER, type);
+ }
+
+ if (err) {
+ error_report_err(err);
+ }
+}
+
void hmp_block_resize(Monitor *mon, const QDict *qdict)
{
const char *device = qdict_get_str(qdict, "device");
diff --git a/hmp.h b/hmp.h
index 093d65f..6bb6499 100644
--- a/hmp.h
+++ b/hmp.h
@@ -55,6 +55,7 @@ void hmp_nmi(Monitor *mon, const QDict *qdict);
void hmp_set_link(Monitor *mon, const QDict *qdict);
void hmp_block_passwd(Monitor *mon, const QDict *qdict);
void hmp_balloon(Monitor *mon, const QDict *qdict);
+void hmp_balloon_drop_cache(Monitor *mon, const QDict *qdict);
void hmp_block_resize(Monitor *mon, const QDict *qdict);
void hmp_snapshot_blkdev(Monitor *mon, const QDict *qdict);
void hmp_snapshot_blkdev_internal(Monitor *mon, const QDict *qdict);
@@ -120,6 +121,8 @@ void watchdog_action_completion(ReadLineState *rs, int nb_args,
const char *str);
void migrate_set_capability_completion(ReadLineState *rs, int nb_args,
const char *str);
+void balloon_drop_cache_completion(ReadLineState *rs, int nb_args,
+ const char *str);
void migrate_set_parameter_completion(ReadLineState *rs, int nb_args,
const char *str);
void host_net_add_completion(ReadLineState *rs, int nb_args, const char *str);
diff --git a/monitor.c b/monitor.c
index a27e115..eefdf3d 100644
--- a/monitor.c
+++ b/monitor.c
@@ -3367,6 +3367,24 @@ void migrate_set_parameter_completion(ReadLineState *rs, int nb_args,
}
}
+void balloon_drop_cache_completion(ReadLineState *rs, int nb_args,
+ const char *str)
+{
+ size_t len;
+
+ len = strlen(str);
+ readline_set_completion_index(rs, len);
+ if (nb_args == 2) {
+ int i;
+ for (i = 0; i < DROP_CACHE_TYPE__MAX; i++) {
+ const char *name = DropCacheType_lookup[i];
+ if (!strncmp(str, name, len)) {
+ readline_add_completion(rs, name);
+ }
+ }
+ }
+}
+
void host_net_add_completion(ReadLineState *rs, int nb_args, const char *str)
{
int i;
diff --git a/qapi-schema.json b/qapi-schema.json
index 8483bdf..117f70a 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1655,6 +1655,41 @@
{ 'command': 'balloon', 'data': {'value': 'int'} }
##
+# @DropCacheType
+#
+# Cache types enumeration
+#
+# @clean: Drop the clean page cache.
+#
+# @slab: Drop the slab cache.
+#
+# @all: Drop both the clean and the slab cache.
+#
+# Since: 2.7
+##
+{ 'enum': 'DropCacheType', 'data': ['clean', 'slab', 'all'] }
+
+##
+# @balloon_drop_cache:
+#
+# Request the vm to drop its cache.
+#
+# @value: the type of cache want vm to drop
+#
+# Returns: Nothing on success
+# If the balloon driver is enabled but not functional because the KVM
+# kernel module cannot support it, KvmMissingCap
+# If no balloon device is present, DeviceNotActive
+#
+# Notes: This command just issues a request to the guest. When it returns,
+# the drop cache operation may not have completed. A guest can drop its
+# cache independent of this command.
+#
+# Since: 2.7.0
+##
+{ 'command': 'balloon_drop_cache', 'data': {'value': 'DropCacheType'} }
+
+##
# @Abort
#
# This action can be used to test transaction failure.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 28801a2..6650ba0 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1802,6 +1802,29 @@ Example:
EQMP
{
+ .name = "balloon_drop_cache",
+ .args_type = "value:i",
+ .mhandler.cmd_new = qmp_marshal_balloon_drop_cache,
+ },
+
+SQMP
+balloon_drop_cache
+-------
+
+Request VM to drop its cache.
+
+Arguments:
+
+- "value": cache type to drop (json-int)
+
+Example:
+
+-> { "execute": "balloon_drop_cache", "arguments": { "value": 1 } }
+<- { "return": {} }
+
+EQMP
+
+ {
.name = "set_link",
.args_type = "name:s,up:b",
.mhandler.cmd_new = qmp_marshal_set_link,
--
1.9.1
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