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unit: reduce heap usage for unit objects 

The storage of the unit objects on the heap is currently not very
efficient. For every unit object we allocate a chunk of memory as large
as the biggest unit type, although there are significant differences in
the units' real requirements.
pahole shows the following sizes of structs:
488  Target
496  Snapshot
512  Device
528  Path
560  Timer
576  Automount
1080 Socket
1160 Swap
1168 Service
1280 Mount

Usually there aren't many targets or snapshots in the system, but Device
is one of the most common unit types and for every one we waste
1280 - 512 = 768 bytes.

Fix it by allocating only the right amount for the given unit type.
On my machine (x86_64, with 39 LVM volumes) this decreases systemd's
USS (unique set size) by more than 300 KB.
This commit is contained in:
Michal Schmidt 2012-01-15 10:53:49 +01:00
parent 1637a8be55
commit 7d17cfbc46
13 changed files with 52 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/automount.c
View File

@ -836,6 +836,7 @@ DEFINE_STRING_TABLE_LOOKUP(automount_state, AutomountState);
const UnitVTable automount_vtable = {
.suffix = ".automount",
.object_size = sizeof(Automount),
.sections =
"Unit\0"
"Automount\0"

7
src/device.c
View File

@ -198,10 +198,12 @@ static int device_update_unit(Manager *m, struct udev_device *dev, const char *p
if (!u) {
delete = true;
if (!(u = unit_new(m)))
u = unit_new(m, sizeof(Device));
if (!u)
return -ENOMEM;
if ((r = device_add_escaped_name(u, path)) < 0)
r = device_add_escaped_name(u, path);
if (r < 0)
goto fail;
unit_add_to_load_queue(u);
@ -583,6 +585,7 @@ DEFINE_STRING_TABLE_LOOKUP(device_state, DeviceState);
const UnitVTable device_vtable = {
.suffix = ".device",
.object_size = sizeof(Device),
.sections =
"Unit\0"
"Device\0"

17
src/manager.c
View File

@ -1795,6 +1795,7 @@ unsigned manager_dispatch_load_queue(Manager *m) {
int manager_load_unit_prepare(Manager *m, const char *name, const char *path, DBusError *e, Unit **_ret) {
Unit *ret;
UnitType t;
int r;
assert(m);
@ -1811,24 +1812,30 @@ int manager_load_unit_prepare(Manager *m, const char *name, const char *path, DB
if (!name)
name = file_name_from_path(path);
if (!unit_name_is_valid(name, false)) {
t = unit_name_to_type(name);
if (t == _UNIT_TYPE_INVALID || !unit_name_is_valid_no_type(name, false)) {
dbus_set_error(e, BUS_ERROR_INVALID_NAME, "Unit name %s is not valid.", name);
return -EINVAL;
}
if ((ret = manager_get_unit(m, name))) {
ret = manager_get_unit(m, name);
if (ret) {
*_ret = ret;
return 1;
}
if (!(ret = unit_new(m)))
ret = unit_new(m, unit_vtable[t]->object_size);
if (!ret)
return -ENOMEM;
if (path)
if (!(ret->meta.fragment_path = strdup(path))) {
if (path) {
ret->meta.fragment_path = strdup(path);
if (!ret->meta.fragment_path) {
unit_free(ret);
return -ENOMEM;
}
}
if ((r = unit_add_name(ret, name)) < 0) {
unit_free(ret);

13
src/mount.c
View File

@ -1395,13 +1395,16 @@ static int mount_add_one(
if (!is_path(where))
return 0;
if (!(e = unit_name_from_path(where, ".mount")))
e = unit_name_from_path(where, ".mount");
if (!e)
return -ENOMEM;
if (!(u = manager_get_unit(m, e))) {
u = manager_get_unit(m, e);
if (!u) {
delete = true;
if (!(u = unit_new(m))) {
u = unit_new(m, sizeof(Mount));
if (!u) {
free(e);
return -ENOMEM;
}
@ -1412,7 +1415,8 @@ static int mount_add_one(
if (r < 0)
goto fail;
if (!(MOUNT(u)->where = strdup(where))) {
MOUNT(u)->where = strdup(where);
if (!MOUNT(u)->where) {
r = -ENOMEM;
goto fail;
}
@ -1837,6 +1841,7 @@ DEFINE_STRING_TABLE_LOOKUP(mount_exec_command, MountExecCommand);
const UnitVTable mount_vtable = {
.suffix = ".mount",
.object_size = sizeof(Mount),
.sections =
"Unit\0"
"Mount\0"

1
src/path.c
View File

@ -717,6 +717,7 @@ DEFINE_STRING_TABLE_LOOKUP(path_type, PathType);
const UnitVTable path_vtable = {
.suffix = ".path",
.object_size = sizeof(Path),
.sections =
"Unit\0"
"Path\0"

1
src/service.c
View File

@ -3553,6 +3553,7 @@ DEFINE_STRING_TABLE_LOOKUP(notify_access, NotifyAccess);
const UnitVTable service_vtable = {
.suffix = ".service",
.object_size = sizeof(Service),
.sections =
"Unit\0"
"Service\0"

1
src/snapshot.c
View File

@ -282,6 +282,7 @@ DEFINE_STRING_TABLE_LOOKUP(snapshot_state, SnapshotState);
const UnitVTable snapshot_vtable = {
.suffix = ".snapshot",
.object_size = sizeof(Snapshot),
.no_alias = true,
.no_instances = true,

1
src/socket.c
View File

@ -2114,6 +2114,7 @@ DEFINE_STRING_TABLE_LOOKUP(socket_exec_command, SocketExecCommand);
const UnitVTable socket_vtable = {
.suffix = ".socket",
.object_size = sizeof(Socket),
.sections =
"Unit\0"
"Socket\0"

13
src/swap.c
View File

@ -334,7 +334,8 @@ int swap_add_one(
assert(m);
assert(what);
if (!(e = unit_name_from_path(what, ".swap")))
e = unit_name_from_path(what, ".swap");
if (!e)
return -ENOMEM;
u = manager_get_unit(m, e);
@ -348,15 +349,18 @@ int swap_add_one(
if (!u) {
delete = true;
if (!(u = unit_new(m))) {
u = unit_new(m, sizeof(Swap));
if (!u) {
free(e);
return -ENOMEM;
}
if ((r = unit_add_name(u, e)) < 0)
r = unit_add_name(u, e);
if (r < 0)
goto fail;
if (!(SWAP(u)->what = strdup(what))) {
SWAP(u)->what = strdup(what);
if (!SWAP(u)->what) {
r = -ENOMEM;
goto fail;
}
@ -1341,6 +1345,7 @@ DEFINE_STRING_TABLE_LOOKUP(swap_exec_command, SwapExecCommand);
const UnitVTable swap_vtable = {
.suffix = ".swap",
.object_size = sizeof(Swap),
.sections =
"Unit\0"
"Swap\0"

1
src/target.c
View File

@ -199,6 +199,7 @@ DEFINE_STRING_TABLE_LOOKUP(target_state, TargetState);
const UnitVTable target_vtable = {
.suffix = ".target",
.object_size = sizeof(Target),
.sections =
"Unit\0"
"Target\0"

1
src/timer.c
View File

@ -468,6 +468,7 @@ DEFINE_STRING_TABLE_LOOKUP(timer_base, TimerBase);
const UnitVTable timer_vtable = {
.suffix = ".timer",
.object_size = sizeof(Timer),
.sections =
"Unit\0"
"Timer\0"

9
src/unit.c
View File

@ -57,15 +57,18 @@ const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX] = {
[UNIT_PATH] = &path_vtable
};
Unit *unit_new(Manager *m) {
Unit *unit_new(Manager *m, size_t size) {
Unit *u;
assert(m);
assert(size >= sizeof(Meta));
if (!(u = new0(Unit, 1)))
u = malloc0(size);
if (!u)
return NULL;
if (!(u->meta.names = set_new(string_hash_func, string_compare_func))) {
u->meta.names = set_new(string_hash_func, string_compare_func);
if (!u->meta.names) {
free(u);
return NULL;
}

5
src/unit.h
View File

@ -286,6 +286,9 @@ union Unit {
struct UnitVTable {
const char *suffix;
/* How much memory does an object of this unit type need */
size_t object_size;
/* Config file sections this unit type understands, separated
* by NUL chars */
const char *sections;
@ -435,7 +438,7 @@ DEFINE_CAST(SNAPSHOT, Snapshot);
DEFINE_CAST(SWAP, Swap);
DEFINE_CAST(PATH, Path);
Unit *unit_new(Manager *m);
Unit *unit_new(Manager *m, size_t size);
void unit_free(Unit *u);
int unit_add_name(Unit *u, const char *name);