To enable targeted reclaim, the list_lru structure distributes its
elements among several LRU lists. Currently, there is one LRU per NUMA
node, and the elements from different nodes are placed to different
LRUs. As a result there are two versions of count and walk functions:
- list_lru_count, list_lru_walk - count, walk items from all nodes;
- list_lru_count_node, list_lru_walk_node - count, walk items from a
particular node specified in an additional argument.
We are going to make the list_lru structure per-memcg in addition to
being per-node. This would allow us to reclaim slab not only on global
memory shortage, but also on memcg pressure. If we followed the current
list_lru interface notation, we would have to add a bunch of new
functions taking a memcg and a node in additional arguments, which would
look cumbersome.
To avoid this, we remove the *_node functions and make list_lru_count
and list_lru_walk require a shrink_control argument so that they will
operate only on the NUMA node specified in shrink_control::nid. If the
caller passes NULL instead of a shrink_control object, the functions
will scan all nodes. This looks sane, because targeted list_lru walks are
only used by shrinkers, which always have a shrink_control object.
Furthermore, when we implement targeted memcg shrinking and add the
memcg field to the shrink_control structure, we will not need to change
the existing list_lru interface.
Thanks to David Chinner for the tip.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Glauber Costa <glommer@xxxxxxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dcache.c | 17 +++++++++--------
fs/gfs2/quota.c | 8 ++++----
fs/inode.c | 8 ++++----
fs/internal.h | 9 +++++----
fs/super.c | 14 ++++++--------
fs/xfs/xfs_buf.c | 14 ++++++++------
fs/xfs/xfs_qm.c | 6 +++---
include/linux/list_lru.h | 43 ++++++++++---------------------------------
mm/list_lru.c | 45 ++++++++++++++++++++++++++++++++++++++++-----
9 files changed, 89 insertions(+), 75 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 4bdb300..aac0e61 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -972,8 +972,8 @@ dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg)
/**
* prune_dcache_sb - shrink the dcache
* @sb: superblock
- * @nr_to_scan : number of entries to try to free
- * @nid: which node to scan for freeable entities
+ * @sc: shrink control, passed to list_lru_walk()
+ * @nr_to_scan: number of entries to try to free
*
* Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
* done when we need more memory an called from the superblock shrinker
@@ -982,14 +982,14 @@ dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg)
* This function may fail to free any resources if all the dentries are in
* use.
*/
-long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan,
- int nid)
+long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc,
+ unsigned long nr_to_scan)
{
LIST_HEAD(dispose);
long freed;
- freed = list_lru_walk_node(&sb->s_dentry_lru, nid, dentry_lru_isolate,
- &dispose, &nr_to_scan);
+ freed = list_lru_walk(&sb->s_dentry_lru, sc, dentry_lru_isolate,
+ &dispose, &nr_to_scan);
shrink_dentry_list(&dispose);
return freed;
}
@@ -1028,9 +1028,10 @@ void shrink_dcache_sb(struct super_block *sb)
do {
LIST_HEAD(dispose);
+ unsigned long nr_to_scan = ULONG_MAX;
- freed = list_lru_walk(&sb->s_dentry_lru,
- dentry_lru_isolate_shrink, &dispose, UINT_MAX);
+ freed = list_lru_walk(&sb->s_dentry_lru, NULL,
+ dentry_lru_isolate_shrink, &dispose, &nr_to_scan);
this_cpu_sub(nr_dentry_unused, freed);
shrink_dentry_list(&dispose);
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 98236d0..f0435da 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -132,8 +132,8 @@ static unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
if (!(sc->gfp_mask & __GFP_FS))
return SHRINK_STOP;
- freed = list_lru_walk_node(&gfs2_qd_lru, sc->nid, gfs2_qd_isolate,
- &dispose, &sc->nr_to_scan);
+ freed = list_lru_walk(&gfs2_qd_lru, sc, gfs2_qd_isolate,
+ &dispose, &sc->nr_to_scan);
gfs2_qd_dispose(&dispose);
@@ -143,7 +143,7 @@ static unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
static unsigned long gfs2_qd_shrink_count(struct shrinker *shrink,
struct shrink_control *sc)
{
- return vfs_pressure_ratio(list_lru_count_node(&gfs2_qd_lru, sc->nid));
+ return vfs_pressure_ratio(list_lru_count(&gfs2_qd_lru, sc));
}
struct shrinker gfs2_qd_shrinker = {
@@ -1504,7 +1504,7 @@ static int gfs2_quota_get_xstate(struct super_block *sb,
}
fqs->qs_uquota.qfs_nextents = 1; /* unsupported */
fqs->qs_gquota = fqs->qs_uquota; /* its the same inode in both cases */
- fqs->qs_incoredqs = list_lru_count(&gfs2_qd_lru);
+ fqs->qs_incoredqs = list_lru_count(&gfs2_qd_lru, NULL);
return 0;
}
diff --git a/fs/inode.c b/fs/inode.c
index 4bcdad3..7c6eda2 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -748,14 +748,14 @@ inode_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg)
* to trim from the LRU. Inodes to be freed are moved to a temporary list and
* then are freed outside inode_lock by dispose_list().
*/
-long prune_icache_sb(struct super_block *sb, unsigned long nr_to_scan,
- int nid)
+long prune_icache_sb(struct super_block *sb, struct shrink_control *sc,
+ unsigned long nr_to_scan)
{
LIST_HEAD(freeable);
long freed;
- freed = list_lru_walk_node(&sb->s_inode_lru, nid, inode_lru_isolate,
- &freeable, &nr_to_scan);
+ freed = list_lru_walk(&sb->s_inode_lru, sc, inode_lru_isolate,
+ &freeable, &nr_to_scan);
dispose_list(&freeable);
return freed;
}
diff --git a/fs/internal.h b/fs/internal.h
index 4657424..a6a9627 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -14,6 +14,7 @@ struct file_system_type;
struct linux_binprm;
struct path;
struct mount;
+struct shrink_control;
/*
* block_dev.c
@@ -107,8 +108,8 @@ extern int open_check_o_direct(struct file *f);
* inode.c
*/
extern spinlock_t inode_sb_list_lock;
-extern long prune_icache_sb(struct super_block *sb, unsigned long nr_to_scan,
- int nid);
+extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc,
+ unsigned long nr_to_scan);
extern void inode_add_lru(struct inode *inode);
/*
@@ -125,8 +126,8 @@ extern int invalidate_inodes(struct super_block *, bool);
*/
extern struct dentry *__d_alloc(struct super_block *, const struct qstr *);
extern int d_set_mounted(struct dentry *dentry);
-extern long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan,
- int nid);
+extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc,
+ unsigned long nr_to_scan);
/*
* read_write.c
diff --git a/fs/super.c b/fs/super.c
index e5f6c2c..a039dba 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -78,8 +78,8 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
if (sb->s_op->nr_cached_objects)
fs_objects = sb->s_op->nr_cached_objects(sb, sc->nid);
- inodes = list_lru_count_node(&sb->s_inode_lru, sc->nid);
- dentries = list_lru_count_node(&sb->s_dentry_lru, sc->nid);
+ inodes = list_lru_count(&sb->s_inode_lru, sc);
+ dentries = list_lru_count(&sb->s_dentry_lru, sc);
total_objects = dentries + inodes + fs_objects + 1;
/* proportion the scan between the caches */
@@ -90,8 +90,8 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
* prune the dcache first as the icache is pinned by it, then
* prune the icache, followed by the filesystem specific caches
*/
- freed = prune_dcache_sb(sb, dentries, sc->nid);
- freed += prune_icache_sb(sb, inodes, sc->nid);
+ freed = prune_dcache_sb(sb, sc, dentries);
+ freed += prune_icache_sb(sb, sc, inodes);
if (fs_objects) {
fs_objects = mult_frac(sc->nr_to_scan, fs_objects,
@@ -119,10 +119,8 @@ static unsigned long super_cache_count(struct shrinker *shrink,
total_objects = sb->s_op->nr_cached_objects(sb,
sc->nid);
- total_objects += list_lru_count_node(&sb->s_dentry_lru,
- sc->nid);
- total_objects += list_lru_count_node(&sb->s_inode_lru,
- sc->nid);
+ total_objects += list_lru_count(&sb->s_dentry_lru, sc);
+ total_objects += list_lru_count(&sb->s_inode_lru, sc);
total_objects = vfs_pressure_ratio(total_objects);
drop_super(sb);
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index c7f0b77..5b2a49c 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1508,9 +1508,11 @@ xfs_wait_buftarg(
int loop = 0;
/* loop until there is nothing left on the lru list. */
- while (list_lru_count(&btp->bt_lru)) {
- list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
- &dispose, LONG_MAX);
+ while (list_lru_count(&btp->bt_lru, NULL)) {
+ unsigned long nr_to_scan = ULONG_MAX;
+
+ list_lru_walk(&btp->bt_lru, NULL, xfs_buftarg_wait_rele,
+ &dispose, &nr_to_scan);
while (!list_empty(&dispose)) {
struct xfs_buf *bp;
@@ -1565,8 +1567,8 @@ xfs_buftarg_shrink_scan(
unsigned long freed;
unsigned long nr_to_scan = sc->nr_to_scan;
- freed = list_lru_walk_node(&btp->bt_lru, sc->nid, xfs_buftarg_isolate,
- &dispose, &nr_to_scan);
+ freed = list_lru_walk(&btp->bt_lru, sc, xfs_buftarg_isolate,
+ &dispose, &nr_to_scan);
while (!list_empty(&dispose)) {
struct xfs_buf *bp;
@@ -1585,7 +1587,7 @@ xfs_buftarg_shrink_count(
{
struct xfs_buftarg *btp = container_of(shrink,
struct xfs_buftarg, bt_shrinker);
- return list_lru_count_node(&btp->bt_lru, sc->nid);
+ return list_lru_count(&btp->bt_lru, sc);
}
void
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 14a4996..aaacf8f 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -769,8 +769,8 @@ xfs_qm_shrink_scan(
INIT_LIST_HEAD(&isol.buffers);
INIT_LIST_HEAD(&isol.dispose);
- freed = list_lru_walk_node(&qi->qi_lru, sc->nid, xfs_qm_dquot_isolate, &isol,
- &nr_to_scan);
+ freed = list_lru_walk(&qi->qi_lru, sc, xfs_qm_dquot_isolate, &isol,
+ &nr_to_scan);
error = xfs_buf_delwri_submit(&isol.buffers);
if (error)
@@ -795,7 +795,7 @@ xfs_qm_shrink_count(
struct xfs_quotainfo *qi = container_of(shrink,
struct xfs_quotainfo, qi_shrinker);
- return list_lru_count_node(&qi->qi_lru, sc->nid);
+ return list_lru_count(&qi->qi_lru, sc);
}
/*
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
index 3ce5417..34e57af 100644
--- a/include/linux/list_lru.h
+++ b/include/linux/list_lru.h
@@ -10,6 +10,8 @@
#include <linux/list.h>
#include <linux/nodemask.h>
+struct shrink_control;
+
/* list_lru_walk_cb has to always return one of those */
enum lru_status {
LRU_REMOVED, /* item removed from list */
@@ -66,32 +68,22 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item);
bool list_lru_del(struct list_lru *lru, struct list_head *item);
/**
- * list_lru_count_node: return the number of objects currently held by @lru
+ * list_lru_count: return the number of objects currently held by @lru
* @lru: the lru pointer.
- * @nid: the node id to count from.
+ * @sc: if not NULL, count only from node @sc->nid.
*
* Always return a non-negative number, 0 for empty lists. There is no
* guarantee that the list is not updated while the count is being computed.
* Callers that want such a guarantee need to provide an outer lock.
*/
-unsigned long list_lru_count_node(struct list_lru *lru, int nid);
-static inline unsigned long list_lru_count(struct list_lru *lru)
-{
- long count = 0;
- int nid;
-
- for_each_node_mask(nid, lru->active_nodes)
- count += list_lru_count_node(lru, nid);
-
- return count;
-}
+unsigned long list_lru_count(struct list_lru *lru, struct shrink_control *sc);
typedef enum lru_status
(*list_lru_walk_cb)(struct list_head *item, spinlock_t *lock, void *cb_arg);
/**
- * list_lru_walk_node: walk a list_lru, isolating and disposing freeable items.
+ * list_lru_walk: walk a list_lru, isolating and disposing freeable items.
* @lru: the lru pointer.
- * @nid: the node id to scan from.
+ * @sc: if not NULL, scan only from node @sc->nid.
* @isolate: callback function that is resposible for deciding what to do with
* the item currently being scanned
* @cb_arg: opaque type that will be passed to @isolate
@@ -109,23 +101,8 @@ typedef enum lru_status
*
* Return value: the number of objects effectively removed from the LRU.
*/
-unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
- list_lru_walk_cb isolate, void *cb_arg,
- unsigned long *nr_to_walk);
-
-static inline unsigned long
-list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
- void *cb_arg, unsigned long nr_to_walk)
-{
- long isolated = 0;
- int nid;
+unsigned long list_lru_walk(struct list_lru *lru, struct shrink_control *sc,
+ list_lru_walk_cb isolate, void *cb_arg,
+ unsigned long *nr_to_walk);
- for_each_node_mask(nid, lru->active_nodes) {
- isolated += list_lru_walk_node(lru, nid, isolate,
- cb_arg, &nr_to_walk);
- if (nr_to_walk <= 0)
- break;
- }
- return isolated;
-}
#endif /* _LRU_LIST_H */
diff --git a/mm/list_lru.c b/mm/list_lru.c
index 72f9dec..7d4a9c2 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -7,8 +7,9 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
-#include <linux/list_lru.h>
#include <linux/slab.h>
+#include <linux/shrinker.h>
+#include <linux/list_lru.h>
bool list_lru_add(struct list_lru *lru, struct list_head *item)
{
@@ -48,7 +49,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item)
}
EXPORT_SYMBOL_GPL(list_lru_del);
-unsigned long
+static unsigned long
list_lru_count_node(struct list_lru *lru, int nid)
{
unsigned long count = 0;
@@ -61,9 +62,23 @@ list_lru_count_node(struct list_lru *lru, int nid)
return count;
}
-EXPORT_SYMBOL_GPL(list_lru_count_node);
-unsigned long
+unsigned long list_lru_count(struct list_lru *lru, struct shrink_control *sc)
+{
+ long count = 0;
+ int nid;
+
+ if (sc)
+ return list_lru_count_node(lru, sc->nid);
+
+ for_each_node_mask(nid, lru->active_nodes)
+ count += list_lru_count_node(lru, nid);
+
+ return count;
+}
+EXPORT_SYMBOL_GPL(list_lru_count);
+
+static unsigned long
list_lru_walk_node(struct list_lru *lru, int nid, list_lru_walk_cb isolate,
void *cb_arg, unsigned long *nr_to_walk)
{
@@ -112,7 +127,27 @@ restart:
spin_unlock(&nlru->lock);
return isolated;
}
-EXPORT_SYMBOL_GPL(list_lru_walk_node);
+
+unsigned long list_lru_walk(struct list_lru *lru, struct shrink_control *sc,
+ list_lru_walk_cb isolate, void *cb_arg,
+ unsigned long *nr_to_walk)
+{
+ long isolated = 0;
+ int nid;
+
+ if (sc)
+ return list_lru_walk_node(lru, sc->nid, isolate,
+ cb_arg, nr_to_walk);
+
+ for_each_node_mask(nid, lru->active_nodes) {
+ isolated += list_lru_walk_node(lru, nid, isolate,
+ cb_arg, nr_to_walk);
+ if (*nr_to_walk <= 0)
+ break;
+ }
+ return isolated;
+}
+EXPORT_SYMBOL_GPL(list_lru_walk);
int list_lru_init(struct list_lru *lru)
{
--
1.7.10.4
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