* [PATCH] util/qemu-config: Remove unnecessary traversal
@ 2023-11-13 14:19 Shiyuan Gao via
2023-11-28 8:21 ` Markus Armbruster
0 siblings, 1 reply; 2+ messages in thread
From: Shiyuan Gao via @ 2023-11-13 14:19 UTC (permalink / raw)
To: Markus Armbruster, Juan Quintela, Konstantin Kostiuk,
Philippe Mathieu-Daudé, Dr. David Alan Gilbert
Cc: qemu-devel, Gao Shiyuan
From: Gao Shiyuan <gaoshiyuan@baidu.com>
No remove QemuOptsList from *_config_groups, so no need to
traverse from the beginning every time.
No functional changes.
Signed-off-by: Gao Shiyuan <gaoshiyuan@baidu.com>
---
include/qemu/config-file.h | 3 +++
util/qemu-config.c | 18 ++++++++----------
2 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/include/qemu/config-file.h b/include/qemu/config-file.h
index b82a778123..223ef7bc8f 100644
--- a/include/qemu/config-file.h
+++ b/include/qemu/config-file.h
@@ -1,6 +1,9 @@
#ifndef QEMU_CONFIG_FILE_H
#define QEMU_CONFIG_FILE_H
+#define MAX_VM_CONFIG_GROUPS 48
+#define MAX_DRIVE_CONFIG_GROUPS 5
+
typedef void QEMUConfigCB(const char *group, QDict *qdict, void *opaque, Error **errp);
void qemu_load_module_for_opts(const char *group);
diff --git a/util/qemu-config.c b/util/qemu-config.c
index 42076efe1e..d7bab2047f 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -9,8 +9,8 @@
#include "qemu/config-file.h"
#include "hw/boards.h"
-static QemuOptsList *vm_config_groups[48];
-static QemuOptsList *drive_config_groups[5];
+static QemuOptsList *vm_config_groups[MAX_VM_CONFIG_GROUPS];
+static QemuOptsList *drive_config_groups[MAX_DRIVE_CONFIG_GROUPS];
static QemuOptsList *find_list(QemuOptsList **lists, const char *group,
Error **errp)
@@ -260,11 +260,10 @@ QemuOptsList *qemu_find_opts_err(const char *group, Error **errp)
void qemu_add_drive_opts(QemuOptsList *list)
{
- int entries, i;
+ static int i;
+ static int entries = MAX_DRIVE_CONFIG_GROUPS - 1; /* keep list NULL terminated */
- entries = ARRAY_SIZE(drive_config_groups);
- entries--; /* keep list NULL terminated */
- for (i = 0; i < entries; i++) {
+ for (; i < entries; i++) {
if (drive_config_groups[i] == NULL) {
drive_config_groups[i] = list;
return;
@@ -276,11 +275,10 @@ void qemu_add_drive_opts(QemuOptsList *list)
void qemu_add_opts(QemuOptsList *list)
{
- int entries, i;
+ static int i;
+ static int entries = MAX_VM_CONFIG_GROUPS - 1; /* keep list NULL terminated */
- entries = ARRAY_SIZE(vm_config_groups);
- entries--; /* keep list NULL terminated */
- for (i = 0; i < entries; i++) {
+ for (; i < entries; i++) {
if (vm_config_groups[i] == NULL) {
vm_config_groups[i] = list;
return;
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] util/qemu-config: Remove unnecessary traversal
2023-11-13 14:19 [PATCH] util/qemu-config: Remove unnecessary traversal Shiyuan Gao via
@ 2023-11-28 8:21 ` Markus Armbruster
0 siblings, 0 replies; 2+ messages in thread
From: Markus Armbruster @ 2023-11-28 8:21 UTC (permalink / raw)
To: Shiyuan Gao via
Cc: Markus Armbruster, Juan Quintela, Konstantin Kostiuk,
Philippe Mathieu-Daudé, Dr. David Alan Gilbert, Shiyuan Gao
Shiyuan Gao via <qemu-devel@nongnu.org> writes:
> From: Gao Shiyuan <gaoshiyuan@baidu.com>
>
> No remove QemuOptsList from *_config_groups, so no need to
> traverse from the beginning every time.
>
> No functional changes.
>
> Signed-off-by: Gao Shiyuan <gaoshiyuan@baidu.com>
> ---
> include/qemu/config-file.h | 3 +++
> util/qemu-config.c | 18 ++++++++----------
> 2 files changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/include/qemu/config-file.h b/include/qemu/config-file.h
> index b82a778123..223ef7bc8f 100644
> --- a/include/qemu/config-file.h
> +++ b/include/qemu/config-file.h
> @@ -1,6 +1,9 @@
> #ifndef QEMU_CONFIG_FILE_H
> #define QEMU_CONFIG_FILE_H
>
> +#define MAX_VM_CONFIG_GROUPS 48
> +#define MAX_DRIVE_CONFIG_GROUPS 5
These are not used outside qemu-config.c, so it's better to define them
there.
> +
> typedef void QEMUConfigCB(const char *group, QDict *qdict, void *opaque, Error **errp);
>
> void qemu_load_module_for_opts(const char *group);
> diff --git a/util/qemu-config.c b/util/qemu-config.c
> index 42076efe1e..d7bab2047f 100644
> --- a/util/qemu-config.c
> +++ b/util/qemu-config.c
> @@ -9,8 +9,8 @@
> #include "qemu/config-file.h"
> #include "hw/boards.h"
>
> -static QemuOptsList *vm_config_groups[48];
> -static QemuOptsList *drive_config_groups[5];
> +static QemuOptsList *vm_config_groups[MAX_VM_CONFIG_GROUPS];
> +static QemuOptsList *drive_config_groups[MAX_DRIVE_CONFIG_GROUPS];
>
> static QemuOptsList *find_list(QemuOptsList **lists, const char *group,
> Error **errp)
> @@ -260,11 +260,10 @@ QemuOptsList *qemu_find_opts_err(const char *group, Error **errp)
>
> void qemu_add_drive_opts(QemuOptsList *list)
> {
> - int entries, i;
> + static int i;
> + static int entries = MAX_DRIVE_CONFIG_GROUPS - 1; /* keep list NULL terminated */
>
> - entries = ARRAY_SIZE(drive_config_groups);
> - entries--; /* keep list NULL terminated */
> - for (i = 0; i < entries; i++) {
> + for (; i < entries; i++) {
> if (drive_config_groups[i] == NULL) {
> drive_config_groups[i] = list;
> return;
> @@ -276,11 +275,10 @@ void qemu_add_drive_opts(QemuOptsList *list)
>
> void qemu_add_opts(QemuOptsList *list)
> {
> - int entries, i;
> + static int i;
> + static int entries = MAX_VM_CONFIG_GROUPS - 1; /* keep list NULL terminated */
>
> - entries = ARRAY_SIZE(vm_config_groups);
> - entries--; /* keep list NULL terminated */
> - for (i = 0; i < entries; i++) {
> + for (; i < entries; i++) {
> if (vm_config_groups[i] == NULL) {
> vm_config_groups[i] = list;
> return;
These two functions run at most 4 and 47 times, respectively. I don't
think speeding them up matters. Keeping them simple does.
Your patch conflates two separate changes.
1. Replace use of ARRAY_SIZE() by new macros. Doesn't feel like an
improvement to me.
2. Optimize appending to arrays drive_config_groups[] and
vm_config_groups[].
Let's have a look at 2. without 1.:
diff --git a/util/qemu-config.c b/util/qemu-config.c
index 42076efe1e..7875359eb3 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -260,11 +260,13 @@ QemuOptsList *qemu_find_opts_err(const char *group, Error **errp)
void qemu_add_drive_opts(QemuOptsList *list)
{
- int entries, i;
+ static int i;
+ int entries;
entries = ARRAY_SIZE(drive_config_groups);
entries--; /* keep list NULL terminated */
- for (i = 0; i < entries; i++) {
+
+ for (; i < entries; i++) {
if (drive_config_groups[i] == NULL) {
drive_config_groups[i] = list;
return;
@@ -276,11 +278,13 @@ void qemu_add_drive_opts(QemuOptsList *list)
void qemu_add_opts(QemuOptsList *list)
{
- int entries, i;
+ static int i;
+ int entries;
entries = ARRAY_SIZE(vm_config_groups);
entries--; /* keep list NULL terminated */
- for (i = 0; i < entries; i++) {
+
+ for (; i < entries; i++) {
if (vm_config_groups[i] == NULL) {
vm_config_groups[i] = list;
return;
This is a more focused patch.
It makes the functions faster, which doesn't matter. Does it make the
functions easier to understand? That would matter.
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2023-11-28 8:21 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-11-13 14:19 [PATCH] util/qemu-config: Remove unnecessary traversal Shiyuan Gao via
2023-11-28 8:21 ` Markus Armbruster
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).