mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-27 04:47:05 +00:00
mm/zswap: change zswap_pool kref to percpu_ref
All zswap entries will take a reference of zswap_pool when zswap_store(), and drop it when free. Change it to use the percpu_ref is better for scalability performance. Although percpu_ref use a bit more memory which should be ok for our use case, since we almost have only one zswap_pool to be using. The performance gain is for zswap_store/load hotpath. Testing kernel build (32 threads) in tmpfs with memory.max=2GB. (zswap shrinker and writeback enabled with one 50GB swapfile, on a 128 CPUs x86-64 machine, below is the average of 5 runs) mm-unstable zswap-global-lru real 63.20 63.12 user 1061.75 1062.95 sys 268.74 264.44 [chengming.zhou@linux.dev: fix zswap_pools_lock usages after changing to percpu_ref] Link: https://lkml.kernel.org/r/20240228154954.3028626-1-chengming.zhou@linux.dev Link: https://lkml.kernel.org/r/20240210-zswap-global-lru-v3-2-200495333595@bytedance.com Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Reviewed-by: Nhat Pham <nphamcs@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
parent
bf9b7df23c
commit
94ace3fec8
1 changed files with 33 additions and 15 deletions
48
mm/zswap.c
48
mm/zswap.c
|
@ -173,7 +173,7 @@ struct crypto_acomp_ctx {
|
|||
struct zswap_pool {
|
||||
struct zpool *zpools[ZSWAP_NR_ZPOOLS];
|
||||
struct crypto_acomp_ctx __percpu *acomp_ctx;
|
||||
struct kref kref;
|
||||
struct percpu_ref ref;
|
||||
struct list_head list;
|
||||
struct work_struct release_work;
|
||||
struct hlist_node node;
|
||||
|
@ -305,6 +305,7 @@ static void zswap_update_total_size(void)
|
|||
/*********************************
|
||||
* pool functions
|
||||
**********************************/
|
||||
static void __zswap_pool_empty(struct percpu_ref *ref);
|
||||
|
||||
static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
|
||||
{
|
||||
|
@ -358,13 +359,18 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
|
|||
/* being the current pool takes 1 ref; this func expects the
|
||||
* caller to always add the new pool as the current pool
|
||||
*/
|
||||
kref_init(&pool->kref);
|
||||
ret = percpu_ref_init(&pool->ref, __zswap_pool_empty,
|
||||
PERCPU_REF_ALLOW_REINIT, GFP_KERNEL);
|
||||
if (ret)
|
||||
goto ref_fail;
|
||||
INIT_LIST_HEAD(&pool->list);
|
||||
|
||||
zswap_pool_debug("created", pool);
|
||||
|
||||
return pool;
|
||||
|
||||
ref_fail:
|
||||
cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
|
||||
error:
|
||||
if (pool->acomp_ctx)
|
||||
free_percpu(pool->acomp_ctx);
|
||||
|
@ -437,8 +443,9 @@ static void __zswap_pool_release(struct work_struct *work)
|
|||
|
||||
synchronize_rcu();
|
||||
|
||||
/* nobody should have been able to get a kref... */
|
||||
WARN_ON(kref_get_unless_zero(&pool->kref));
|
||||
/* nobody should have been able to get a ref... */
|
||||
WARN_ON(!percpu_ref_is_zero(&pool->ref));
|
||||
percpu_ref_exit(&pool->ref);
|
||||
|
||||
/* pool is now off zswap_pools list and has no references. */
|
||||
zswap_pool_destroy(pool);
|
||||
|
@ -446,13 +453,13 @@ static void __zswap_pool_release(struct work_struct *work)
|
|||
|
||||
static struct zswap_pool *zswap_pool_current(void);
|
||||
|
||||
static void __zswap_pool_empty(struct kref *kref)
|
||||
static void __zswap_pool_empty(struct percpu_ref *ref)
|
||||
{
|
||||
struct zswap_pool *pool;
|
||||
|
||||
pool = container_of(kref, typeof(*pool), kref);
|
||||
pool = container_of(ref, typeof(*pool), ref);
|
||||
|
||||
spin_lock(&zswap_pools_lock);
|
||||
spin_lock_bh(&zswap_pools_lock);
|
||||
|
||||
WARN_ON(pool == zswap_pool_current());
|
||||
|
||||
|
@ -461,7 +468,7 @@ static void __zswap_pool_empty(struct kref *kref)
|
|||
INIT_WORK(&pool->release_work, __zswap_pool_release);
|
||||
schedule_work(&pool->release_work);
|
||||
|
||||
spin_unlock(&zswap_pools_lock);
|
||||
spin_unlock_bh(&zswap_pools_lock);
|
||||
}
|
||||
|
||||
static int __must_check zswap_pool_get(struct zswap_pool *pool)
|
||||
|
@ -469,12 +476,12 @@ static int __must_check zswap_pool_get(struct zswap_pool *pool)
|
|||
if (!pool)
|
||||
return 0;
|
||||
|
||||
return kref_get_unless_zero(&pool->kref);
|
||||
return percpu_ref_tryget(&pool->ref);
|
||||
}
|
||||
|
||||
static void zswap_pool_put(struct zswap_pool *pool)
|
||||
{
|
||||
kref_put(&pool->kref, __zswap_pool_empty);
|
||||
percpu_ref_put(&pool->ref);
|
||||
}
|
||||
|
||||
static struct zswap_pool *__zswap_pool_current(void)
|
||||
|
@ -591,7 +598,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
|
|||
return -EINVAL;
|
||||
}
|
||||
|
||||
spin_lock(&zswap_pools_lock);
|
||||
spin_lock_bh(&zswap_pools_lock);
|
||||
|
||||
pool = zswap_pool_find_get(type, compressor);
|
||||
if (pool) {
|
||||
|
@ -600,17 +607,28 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
|
|||
list_del_rcu(&pool->list);
|
||||
}
|
||||
|
||||
spin_unlock(&zswap_pools_lock);
|
||||
spin_unlock_bh(&zswap_pools_lock);
|
||||
|
||||
if (!pool)
|
||||
pool = zswap_pool_create(type, compressor);
|
||||
else {
|
||||
/*
|
||||
* Restore the initial ref dropped by percpu_ref_kill()
|
||||
* when the pool was decommissioned and switch it again
|
||||
* to percpu mode.
|
||||
*/
|
||||
percpu_ref_resurrect(&pool->ref);
|
||||
|
||||
/* Drop the ref from zswap_pool_find_get(). */
|
||||
zswap_pool_put(pool);
|
||||
}
|
||||
|
||||
if (pool)
|
||||
ret = param_set_charp(s, kp);
|
||||
else
|
||||
ret = -EINVAL;
|
||||
|
||||
spin_lock(&zswap_pools_lock);
|
||||
spin_lock_bh(&zswap_pools_lock);
|
||||
|
||||
if (!ret) {
|
||||
put_pool = zswap_pool_current();
|
||||
|
@ -625,7 +643,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
|
|||
put_pool = pool;
|
||||
}
|
||||
|
||||
spin_unlock(&zswap_pools_lock);
|
||||
spin_unlock_bh(&zswap_pools_lock);
|
||||
|
||||
if (!zswap_has_pool && !pool) {
|
||||
/* if initial pool creation failed, and this pool creation also
|
||||
|
@ -642,7 +660,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
|
|||
* or the new pool we failed to add
|
||||
*/
|
||||
if (put_pool)
|
||||
zswap_pool_put(put_pool);
|
||||
percpu_ref_kill(&put_pool->ref);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue