On Thu, August 08, 2013 at 07:04 (+0200), Wang Shilong wrote:
> struct __prelim_ref is allocated and freed frequently when
> walking backref tree, using slab allocater can not only
> speed up allocating but also detect memory leaks.
>
> Signed-off-by: Wang Shilong <wangsl.fnst@xxxxxxxxxxxxxx>
> Reviewed-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/backref.c | 30 +++++++++++++++++++++++++-----
> fs/btrfs/backref.h | 2 ++
> fs/btrfs/super.c | 8 ++++++++
> 3 files changed, 35 insertions(+), 5 deletions(-)
>
> diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
> index f7781e6..916e4f1 100644
> --- a/fs/btrfs/backref.c
> +++ b/fs/btrfs/backref.c
> @@ -119,6 +119,26 @@ struct __prelim_ref {
> u64 wanted_disk_byte;
> };
>
> +static struct kmem_cache *prelim_ref_cache;
> +
> +int __init btrfs_prelim_ref_init(void)
> +{
> + prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
> + sizeof(struct __prelim_ref),
> + 0,
> + SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
> + NULL);
> + if (!prelim_ref_cache)
> + return -ENOMEM;
> + return 0;
> +}
> +
> +void btrfs_prelim_ref_exit(void)
> +{
> + if (prelim_ref_cache)
> + kmem_cache_destroy(prelim_ref_cache);
> +}
> +
> /*
> * the rules for all callers of this function are:
> * - obtaining the parent is the goal
> @@ -165,7 +185,7 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
> {
> struct __prelim_ref *ref;
>
> - ref = kmalloc(sizeof(*ref), gfp_mask);
> + ref = kmem_cache_alloc(prelim_ref_cache, gfp_mask);
> if (!ref)
> return -ENOMEM;
>
> @@ -493,7 +513,7 @@ static void __merge_refs(struct list_head *head, int mode)
> ref1->count += ref2->count;
>
> list_del(&ref2->list);
> - kfree(ref2);
> + kmem_cache_free(prelim_ref_cache, ref2);
> }
>
> }
> @@ -958,7 +978,7 @@ again:
> }
> }
> list_del(&ref->list);
> - kfree(ref);
> + kmem_cache_free(prelim_ref_cache, ref);
> }
>
> out:
> @@ -966,13 +986,13 @@ out:
> while (!list_empty(&prefs)) {
> ref = list_first_entry(&prefs, struct __prelim_ref, list);
> list_del(&ref->list);
> - kfree(ref);
> + kmem_cache_free(prelim_ref_cache, ref);
> }
> while (!list_empty(&prefs_delayed)) {
> ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
> list);
> list_del(&ref->list);
> - kfree(ref);
> + kmem_cache_free(prelim_ref_cache, ref);
> }
>
> return ret;
> diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
> index 8f2e767..a910b27 100644
> --- a/fs/btrfs/backref.h
> +++ b/fs/btrfs/backref.h
> @@ -72,4 +72,6 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
> struct btrfs_inode_extref **ret_extref,
> u64 *found_off);
>
> +int __init btrfs_prelim_ref_init(void);
> +void btrfs_prelim_ref_exit(void);
> #endif
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index b64d762..de7eb3d 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -56,6 +56,7 @@
> #include "rcu-string.h"
> #include "dev-replace.h"
> #include "free-space-cache.h"
> +#include "backref.h"
>
> #define CREATE_TRACE_POINTS
> #include <trace/events/btrfs.h>
> @@ -1774,6 +1775,10 @@ static int __init init_btrfs_fs(void)
> if (err)
> goto free_auto_defrag;
>
> + err = btrfs_prelim_ref_init();
> + if (err)
> + goto free_prelim_ref;
> +
> err = btrfs_interface_init();
> if (err)
> goto free_delayed_ref;
> @@ -1791,6 +1796,8 @@ static int __init init_btrfs_fs(void)
>
> unregister_ioctl:
> btrfs_interface_exit();
> +free_prelim_ref:
> + btrfs_prelim_ref_exit();
> free_delayed_ref:
> btrfs_delayed_ref_exit();
> free_auto_defrag:
> @@ -1817,6 +1824,7 @@ static void __exit exit_btrfs_fs(void)
> btrfs_delayed_ref_exit();
> btrfs_auto_defrag_exit();
> btrfs_delayed_inode_exit();
> + btrfs_prelim_ref_exit();
> ordered_data_exit();
> extent_map_exit();
> extent_io_exit();
>
I generally like the idea of using a custom cache here. What about this one?
324 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
[...]
367 /* additional parents require new refs being added here */
368 while ((node = ulist_next(parents, &uiter))) {
369 new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
That new_ref will also be freed with kmem_cache_free after your patch, I think.
Thanks,
-Jan
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