[-next,v8,3/3] mm/zswap: delay the initialization of zswap
Commit Message
Since some users may not use zswap, the zswap_pool is wasted. Save memory
by delaying the initialization of zswap until enabled.
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
---
mm/zswap.c | 56 +++++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 43 insertions(+), 13 deletions(-)
Comments
On Mon, Apr 03, 2023 at 08:13:18PM +0800, Liu Shixin wrote:
> Since some users may not use zswap, the zswap_pool is wasted. Save memory
> by delaying the initialization of zswap until enabled.
>
> Signed-off-by: Liu Shixin <liushixin2@huawei.com>
> ---
> mm/zswap.c | 56 +++++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 43 insertions(+), 13 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 9169c2baee87..14db57450bfd 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -81,6 +81,8 @@ static bool zswap_pool_reached_full;
>
> #define ZSWAP_PARAM_UNSET ""
>
> +static int zswap_setup(void);
> +
> /* Enable/disable zswap */
> static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
> static int zswap_enabled_param_set(const char *,
> @@ -222,6 +224,9 @@ enum zswap_init_type {
>
> static enum zswap_init_type zswap_init_state;
>
> +/* used to ensure the integrity of initialization */
> +static DEFINE_MUTEX(zswap_init_lock);
> +
> /* init completed, but couldn't create the initial pool */
> static bool zswap_has_pool;
>
> @@ -654,7 +659,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> return NULL;
> }
>
> -static __init struct zswap_pool *__zswap_pool_create_fallback(void)
> +static struct zswap_pool *__zswap_pool_create_fallback(void)
> {
> bool has_comp, has_zpool;
>
> @@ -763,21 +768,28 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
> char *s = strstrip((char *)val);
> int ret;
>
> + mutex_lock(&zswap_init_lock);
> switch (zswap_init_state) {
> case ZSWAP_UNINIT:
> /* if this is load-time (pre-init) param setting,
> * don't create a pool; that's done during init.
> */
> - return param_set_charp(s, kp);
> + ret = param_set_charp(s, kp);
> + mutex_unlock(&zswap_init_lock);
> + return ret;
> case ZSWAP_INIT_SUCCEED:
> /* no change required */
> - if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
> + if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool) {
> + mutex_unlock(&zswap_init_lock);
> return 0;
> + }
> break;
> case ZSWAP_INIT_FAILED:
> pr_err("can't set param, initialization failed\n");
> + mutex_unlock(&zswap_init_lock);
> return -ENODEV;
> }
> + mutex_unlock(&zswap_init_lock);
The pattern here looks a bit odd. Can you split the code that
the ZSWAP_INIT_SUCCEED case falls through into a helper, then just
assign ret inside the switch statement, break out and do a single
unlock and return?
> + /*if this is load-time (pre-init) param setting, only set param.*/
missing space after the initial and before the last * here.
But except for these nitpicks this version looks good to me now.
@@ -81,6 +81,8 @@ static bool zswap_pool_reached_full;
#define ZSWAP_PARAM_UNSET ""
+static int zswap_setup(void);
+
/* Enable/disable zswap */
static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
static int zswap_enabled_param_set(const char *,
@@ -222,6 +224,9 @@ enum zswap_init_type {
static enum zswap_init_type zswap_init_state;
+/* used to ensure the integrity of initialization */
+static DEFINE_MUTEX(zswap_init_lock);
+
/* init completed, but couldn't create the initial pool */
static bool zswap_has_pool;
@@ -654,7 +659,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
return NULL;
}
-static __init struct zswap_pool *__zswap_pool_create_fallback(void)
+static struct zswap_pool *__zswap_pool_create_fallback(void)
{
bool has_comp, has_zpool;
@@ -763,21 +768,28 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
char *s = strstrip((char *)val);
int ret;
+ mutex_lock(&zswap_init_lock);
switch (zswap_init_state) {
case ZSWAP_UNINIT:
/* if this is load-time (pre-init) param setting,
* don't create a pool; that's done during init.
*/
- return param_set_charp(s, kp);
+ ret = param_set_charp(s, kp);
+ mutex_unlock(&zswap_init_lock);
+ return ret;
case ZSWAP_INIT_SUCCEED:
/* no change required */
- if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
+ if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool) {
+ mutex_unlock(&zswap_init_lock);
return 0;
+ }
break;
case ZSWAP_INIT_FAILED:
pr_err("can't set param, initialization failed\n");
+ mutex_unlock(&zswap_init_lock);
return -ENODEV;
}
+ mutex_unlock(&zswap_init_lock);
if (!type) {
if (!zpool_has_pool(s)) {
@@ -867,19 +879,30 @@ static int zswap_zpool_param_set(const char *val,
static int zswap_enabled_param_set(const char *val,
const struct kernel_param *kp)
{
+ int ret = -ENODEV;
+
+ /*if this is load-time (pre-init) param setting, only set param.*/
+ if (system_state != SYSTEM_RUNNING)
+ return param_set_bool(val, kp);
+
+ mutex_lock(&zswap_init_lock);
switch (zswap_init_state) {
case ZSWAP_UNINIT:
- return param_set_bool(val, kp);
+ if (zswap_setup())
+ break;
+ fallthrough;
case ZSWAP_INIT_SUCCEED:
- if (!zswap_has_pool) {
+ if (!zswap_has_pool)
pr_err("can't enable, no pool configured\n");
- return -ENODEV;
- } else
- return param_set_bool(val, kp);
+ else
+ ret = param_set_bool(val, kp);
+ break;
case ZSWAP_INIT_FAILED:
pr_err("can't enable, initialization failed\n");
- return -ENODEV;
}
+ mutex_unlock(&zswap_init_lock);
+
+ return ret;
}
/*********************************
@@ -1437,7 +1460,7 @@ static const struct frontswap_ops zswap_frontswap_ops = {
static struct dentry *zswap_debugfs_root;
-static int __init zswap_debugfs_init(void)
+static int zswap_debugfs_init(void)
{
if (!debugfs_initialized())
return -ENODEV;
@@ -1468,7 +1491,7 @@ static int __init zswap_debugfs_init(void)
return 0;
}
#else
-static int __init zswap_debugfs_init(void)
+static int zswap_debugfs_init(void)
{
return 0;
}
@@ -1477,7 +1500,7 @@ static int __init zswap_debugfs_init(void)
/*********************************
* module init and exit
**********************************/
-static int __init init_zswap(void)
+static int zswap_setup(void)
{
struct zswap_pool *pool;
int ret;
@@ -1540,8 +1563,15 @@ static int __init init_zswap(void)
zswap_enabled = false;
return -ENOMEM;
}
+
+static int __init zswap_init(void)
+{
+ if (!zswap_enabled)
+ return 0;
+ return zswap_setup();
+}
/* must be late so crypto has time to come up */
-late_initcall(init_zswap);
+late_initcall(zswap_init);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");