* [PATCH 1/3] mm: add context argument to shrinker callback
2010-07-15 11:46 [PATCH 0/3] shrinker fixes for XFS for 2.6.35 Dave Chinner
@ 2010-07-15 11:46 ` Dave Chinner
2010-07-15 18:09 ` Christoph Hellwig
2010-07-20 19:30 ` Alex Elder
2010-07-15 11:46 ` [PATCH 2/3] xfs: convert inode shrinker to per-filesystem contexts Dave Chinner
2010-07-15 11:46 ` [PATCH 3/3] xfs: track AGs with reclaimable inodes in per-ag radix tree Dave Chinner
2 siblings, 2 replies; 10+ messages in thread
From: Dave Chinner @ 2010-07-15 11:46 UTC (permalink / raw)
To: xfs; +Cc: linux-kernel, linux-fsdevel, linux-mm
From: Dave Chinner <dchinner@redhat.com>
The current shrinker implementation requires the registered callback
to have global state to work from. This makes it difficult to shrink
caches that are not global (e.g. per-filesystem caches). Pass the shrinker
structure to the callback so that users can embed the shrinker structure
in the context the shrinker needs to operate on and get back to it in the
callback via container_of().
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
arch/x86/kvm/mmu.c | 2 +-
drivers/gpu/drm/i915/i915_gem.c | 2 +-
fs/dcache.c | 2 +-
fs/gfs2/glock.c | 2 +-
fs/gfs2/quota.c | 2 +-
fs/gfs2/quota.h | 2 +-
fs/inode.c | 2 +-
fs/mbcache.c | 5 +++--
fs/nfs/dir.c | 2 +-
fs/nfs/internal.h | 3 ++-
fs/quota/dquot.c | 2 +-
fs/ubifs/shrinker.c | 2 +-
fs/ubifs/ubifs.h | 2 +-
fs/xfs/linux-2.6/xfs_buf.c | 5 +++--
fs/xfs/linux-2.6/xfs_sync.c | 1 +
fs/xfs/quota/xfs_qm.c | 7 +++++--
include/linux/mm.h | 2 +-
mm/vmscan.c | 8 +++++---
18 files changed, 31 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 3699613..b1ed0a1 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2926,7 +2926,7 @@ static int kvm_mmu_remove_some_alloc_mmu_pages(struct kvm *kvm)
return kvm_mmu_zap_page(kvm, page) + 1;
}
-static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
+static int mmu_shrink(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
{
struct kvm *kvm;
struct kvm *kvm_freed = NULL;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0743858..3b0b0b1 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4977,7 +4977,7 @@ i915_gpu_is_active(struct drm_device *dev)
}
static int
-i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
+i915_gem_shrink(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
{
drm_i915_private_t *dev_priv, *next_dev;
struct drm_i915_gem_object *obj_priv, *next_obj;
diff --git a/fs/dcache.c b/fs/dcache.c
index c8c78ba..86d4db1 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -896,7 +896,7 @@ EXPORT_SYMBOL(shrink_dcache_parent);
*
* In this case we return -1 to tell the caller that we baled.
*/
-static int shrink_dcache_memory(int nr, gfp_t gfp_mask)
+static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
if (nr) {
if (!(gfp_mask & __GFP_FS))
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index ddcdbf4..04b540c 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1348,7 +1348,7 @@ void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
}
-static int gfs2_shrink_glock_memory(int nr, gfp_t gfp_mask)
+static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
struct gfs2_glock *gl;
int may_demote;
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 49667d6..4ea548f 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -77,7 +77,7 @@ static LIST_HEAD(qd_lru_list);
static atomic_t qd_lru_count = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(qd_lru_lock);
-int gfs2_shrink_qd_memory(int nr, gfp_t gfp_mask)
+int gfs2_shrink_qd_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
struct gfs2_quota_data *qd;
struct gfs2_sbd *sdp;
diff --git a/fs/gfs2/quota.h b/fs/gfs2/quota.h
index 195f60c..e7d236c 100644
--- a/fs/gfs2/quota.h
+++ b/fs/gfs2/quota.h
@@ -51,7 +51,7 @@ static inline int gfs2_quota_lock_check(struct gfs2_inode *ip)
return ret;
}
-extern int gfs2_shrink_qd_memory(int nr, gfp_t gfp_mask);
+extern int gfs2_shrink_qd_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask);
extern const struct quotactl_ops gfs2_quotactl_ops;
#endif /* __QUOTA_DOT_H__ */
diff --git a/fs/inode.c b/fs/inode.c
index 2bee20a..722860b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -512,7 +512,7 @@ static void prune_icache(int nr_to_scan)
* This function is passed the number of inodes to scan, and it returns the
* total number of remaining possibly-reclaimable inodes.
*/
-static int shrink_icache_memory(int nr, gfp_t gfp_mask)
+static int shrink_icache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
if (nr) {
/*
diff --git a/fs/mbcache.c b/fs/mbcache.c
index ec88ff3..e28f21b 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -115,7 +115,7 @@ mb_cache_indexes(struct mb_cache *cache)
* What the mbcache registers as to get shrunk dynamically.
*/
-static int mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask);
+static int mb_cache_shrink_fn(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask);
static struct shrinker mb_cache_shrinker = {
.shrink = mb_cache_shrink_fn,
@@ -191,13 +191,14 @@ forget:
* This function is called by the kernel memory management when memory
* gets low.
*
+ * @shrink: (ignored)
* @nr_to_scan: Number of objects to scan
* @gfp_mask: (ignored)
*
* Returns the number of objects which are present in the cache.
*/
static int
-mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask)
+mb_cache_shrink_fn(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
{
LIST_HEAD(free_list);
struct list_head *l, *ltmp;
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 782b431..e60416d 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1710,7 +1710,7 @@ static void nfs_access_free_list(struct list_head *head)
}
}
-int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
+int nfs_access_cache_shrinker(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
{
LIST_HEAD(head);
struct nfs_inode *nfsi;
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index d8bd619..e70f44b 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -205,7 +205,8 @@ extern struct rpc_procinfo nfs4_procedures[];
void nfs_close_context(struct nfs_open_context *ctx, int is_sync);
/* dir.c */
-extern int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask);
+extern int nfs_access_cache_shrinker(struct shrinker *shrink,
+ int nr_to_scan, gfp_t gfp_mask);
/* inode.c */
extern struct workqueue_struct *nfsiod_workqueue;
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 12c233d..437d2ca 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -676,7 +676,7 @@ static void prune_dqcache(int count)
* This is called from kswapd when we think we need some
* more memory
*/
-static int shrink_dqcache_memory(int nr, gfp_t gfp_mask)
+static int shrink_dqcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
if (nr) {
spin_lock(&dq_list_lock);
diff --git a/fs/ubifs/shrinker.c b/fs/ubifs/shrinker.c
index 02feb59..0b20111 100644
--- a/fs/ubifs/shrinker.c
+++ b/fs/ubifs/shrinker.c
@@ -277,7 +277,7 @@ static int kick_a_thread(void)
return 0;
}
-int ubifs_shrinker(int nr, gfp_t gfp_mask)
+int ubifs_shrinker(struct shrinker *shrink, int nr, gfp_t gfp_mask)
{
int freed, contention = 0;
long clean_zn_cnt = atomic_long_read(&ubifs_clean_zn_cnt);
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 2eef553..0431087 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1575,7 +1575,7 @@ int ubifs_tnc_start_commit(struct ubifs_info *c, struct ubifs_zbranch *zroot);
int ubifs_tnc_end_commit(struct ubifs_info *c);
/* shrinker.c */
-int ubifs_shrinker(int nr_to_scan, gfp_t gfp_mask);
+int ubifs_shrinker(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask);
/* commit.c */
int ubifs_bg_thread(void *info);
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 649ade8..2ee3f7a 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -45,7 +45,7 @@
static kmem_zone_t *xfs_buf_zone;
STATIC int xfsbufd(void *);
-STATIC int xfsbufd_wakeup(int, gfp_t);
+STATIC int xfsbufd_wakeup(struct shrinker *, int, gfp_t);
STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
static struct shrinker xfs_buf_shake = {
.shrink = xfsbufd_wakeup,
@@ -340,7 +340,7 @@ _xfs_buf_lookup_pages(
__func__, gfp_mask);
XFS_STATS_INC(xb_page_retries);
- xfsbufd_wakeup(0, gfp_mask);
+ xfsbufd_wakeup(NULL, 0, gfp_mask);
congestion_wait(BLK_RW_ASYNC, HZ/50);
goto retry;
}
@@ -1762,6 +1762,7 @@ xfs_buf_runall_queues(
STATIC int
xfsbufd_wakeup(
+ struct shrinker *shrink,
int priority,
gfp_t mask)
{
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index ef7f021..be37582 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -838,6 +838,7 @@ static struct rw_semaphore xfs_mount_list_lock;
static int
xfs_reclaim_inode_shrink(
+ struct shrinker *shrink,
int nr_to_scan,
gfp_t gfp_mask)
{
diff --git a/fs/xfs/quota/xfs_qm.c b/fs/xfs/quota/xfs_qm.c
index 8c117ff..67c0183 100644
--- a/fs/xfs/quota/xfs_qm.c
+++ b/fs/xfs/quota/xfs_qm.c
@@ -69,7 +69,7 @@ STATIC void xfs_qm_list_destroy(xfs_dqlist_t *);
STATIC int xfs_qm_init_quotainos(xfs_mount_t *);
STATIC int xfs_qm_init_quotainfo(xfs_mount_t *);
-STATIC int xfs_qm_shake(int, gfp_t);
+STATIC int xfs_qm_shake(struct shrinker *, int, gfp_t);
static struct shrinker xfs_qm_shaker = {
.shrink = xfs_qm_shake,
@@ -2117,7 +2117,10 @@ xfs_qm_shake_freelist(
*/
/* ARGSUSED */
STATIC int
-xfs_qm_shake(int nr_to_scan, gfp_t gfp_mask)
+xfs_qm_shake(
+ struct shrinker *shrink,
+ int nr_to_scan,
+ gfp_t gfp_mask)
{
int ndqused, nfree, n;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b969efb..a2b4804 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -999,7 +999,7 @@ static inline void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
* querying the cache size, so a fastpath for that case is appropriate.
*/
struct shrinker {
- int (*shrink)(int nr_to_scan, gfp_t gfp_mask);
+ int (*shrink)(struct shrinker *, int nr_to_scan, gfp_t gfp_mask);
int seeks; /* seeks to recreate an obj */
/* These are for internal use */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9c7e57c..199fa43 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -213,8 +213,9 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
unsigned long total_scan;
- unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);
+ unsigned long max_pass;
+ max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask);
delta = (4 * scanned) / shrinker->seeks;
delta *= max_pass;
do_div(delta, lru_pages + 1);
@@ -242,8 +243,9 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
int shrink_ret;
int nr_before;
- nr_before = (*shrinker->shrink)(0, gfp_mask);
- shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
+ nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask);
+ shrink_ret = (*shrinker->shrink)(shrinker, this_scan,
+ gfp_mask);
if (shrink_ret == -1)
break;
if (shrink_ret < nr_before)
--
1.7.1
--
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^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH 2/3] xfs: convert inode shrinker to per-filesystem contexts
2010-07-15 11:46 [PATCH 0/3] shrinker fixes for XFS for 2.6.35 Dave Chinner
2010-07-15 11:46 ` [PATCH 1/3] mm: add context argument to shrinker callback Dave Chinner
@ 2010-07-15 11:46 ` Dave Chinner
2010-07-15 18:10 ` Christoph Hellwig
2010-07-20 19:30 ` Alex Elder
2010-07-15 11:46 ` [PATCH 3/3] xfs: track AGs with reclaimable inodes in per-ag radix tree Dave Chinner
2 siblings, 2 replies; 10+ messages in thread
From: Dave Chinner @ 2010-07-15 11:46 UTC (permalink / raw)
To: xfs; +Cc: linux-kernel, linux-fsdevel, linux-mm
From: Dave Chinner <dchinner@redhat.com>
Now the shrinker passes us a context, wire up a shrinker context per
filesystem. This allows us to remove the global mount list and the
locking problems that introduced. It also means that a shrinker call
does not need to traverse clean filesystems before finding a
filesystem with reclaimable inodes. This significantly reduces
scanning overhead when lots of filesystems are present.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/linux-2.6/xfs_super.c | 2 -
fs/xfs/linux-2.6/xfs_sync.c | 62 +++++++++--------------------------------
fs/xfs/linux-2.6/xfs_sync.h | 2 -
fs/xfs/xfs_mount.h | 2 +-
4 files changed, 15 insertions(+), 53 deletions(-)
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index f2d1718..80938c7 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1883,7 +1883,6 @@ init_xfs_fs(void)
goto out_cleanup_procfs;
vfs_initquota();
- xfs_inode_shrinker_init();
error = register_filesystem(&xfs_fs_type);
if (error)
@@ -1911,7 +1910,6 @@ exit_xfs_fs(void)
{
vfs_exitquota();
unregister_filesystem(&xfs_fs_type);
- xfs_inode_shrinker_destroy();
xfs_sysctl_unregister();
xfs_cleanup_procfs();
xfs_buf_terminate();
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index be37582..f433819 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -828,14 +828,7 @@ xfs_reclaim_inodes(
/*
* Shrinker infrastructure.
- *
- * This is all far more complex than it needs to be. It adds a global list of
- * mounts because the shrinkers can only call a global context. We need to make
- * the shrinkers pass a context to avoid the need for global state.
*/
-static LIST_HEAD(xfs_mount_list);
-static struct rw_semaphore xfs_mount_list_lock;
-
static int
xfs_reclaim_inode_shrink(
struct shrinker *shrink,
@@ -847,65 +840,38 @@ xfs_reclaim_inode_shrink(
xfs_agnumber_t ag;
int reclaimable = 0;
+ mp = container_of(shrink, struct xfs_mount, m_inode_shrink);
if (nr_to_scan) {
if (!(gfp_mask & __GFP_FS))
return -1;
- down_read(&xfs_mount_list_lock);
- list_for_each_entry(mp, &xfs_mount_list, m_mplist) {
- xfs_inode_ag_iterator(mp, xfs_reclaim_inode, 0,
+ xfs_inode_ag_iterator(mp, xfs_reclaim_inode, 0,
XFS_ICI_RECLAIM_TAG, 1, &nr_to_scan);
- if (nr_to_scan <= 0)
- break;
- }
- up_read(&xfs_mount_list_lock);
- }
+ /* if we don't exhaust the scan, don't bother coming back */
+ if (nr_to_scan > 0)
+ return -1;
+ }
- down_read(&xfs_mount_list_lock);
- list_for_each_entry(mp, &xfs_mount_list, m_mplist) {
- for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
- pag = xfs_perag_get(mp, ag);
- reclaimable += pag->pag_ici_reclaimable;
- xfs_perag_put(pag);
- }
+ for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
+ pag = xfs_perag_get(mp, ag);
+ reclaimable += pag->pag_ici_reclaimable;
+ xfs_perag_put(pag);
}
- up_read(&xfs_mount_list_lock);
return reclaimable;
}
-static struct shrinker xfs_inode_shrinker = {
- .shrink = xfs_reclaim_inode_shrink,
- .seeks = DEFAULT_SEEKS,
-};
-
-void __init
-xfs_inode_shrinker_init(void)
-{
- init_rwsem(&xfs_mount_list_lock);
- register_shrinker(&xfs_inode_shrinker);
-}
-
-void
-xfs_inode_shrinker_destroy(void)
-{
- ASSERT(list_empty(&xfs_mount_list));
- unregister_shrinker(&xfs_inode_shrinker);
-}
-
void
xfs_inode_shrinker_register(
struct xfs_mount *mp)
{
- down_write(&xfs_mount_list_lock);
- list_add_tail(&mp->m_mplist, &xfs_mount_list);
- up_write(&xfs_mount_list_lock);
+ mp->m_inode_shrink.shrink = xfs_reclaim_inode_shrink;
+ mp->m_inode_shrink.seeks = DEFAULT_SEEKS;
+ register_shrinker(&mp->m_inode_shrink);
}
void
xfs_inode_shrinker_unregister(
struct xfs_mount *mp)
{
- down_write(&xfs_mount_list_lock);
- list_del(&mp->m_mplist);
- up_write(&xfs_mount_list_lock);
+ unregister_shrinker(&mp->m_inode_shrink);
}
diff --git a/fs/xfs/linux-2.6/xfs_sync.h b/fs/xfs/linux-2.6/xfs_sync.h
index cdcbaac..e28139a 100644
--- a/fs/xfs/linux-2.6/xfs_sync.h
+++ b/fs/xfs/linux-2.6/xfs_sync.h
@@ -55,8 +55,6 @@ int xfs_inode_ag_iterator(struct xfs_mount *mp,
int (*execute)(struct xfs_inode *ip, struct xfs_perag *pag, int flags),
int flags, int tag, int write_lock, int *nr_to_scan);
-void xfs_inode_shrinker_init(void);
-void xfs_inode_shrinker_destroy(void);
void xfs_inode_shrinker_register(struct xfs_mount *mp);
void xfs_inode_shrinker_unregister(struct xfs_mount *mp);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 1d2c7ee..5761087 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -259,7 +259,7 @@ typedef struct xfs_mount {
wait_queue_head_t m_wait_single_sync_task;
__int64_t m_update_flags; /* sb flags we need to update
on the next remount,rw */
- struct list_head m_mplist; /* inode shrinker mount list */
+ struct shrinker m_inode_shrink; /* inode reclaim shrinker */
} xfs_mount_t;
/*
--
1.7.1
--
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^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH 3/3] xfs: track AGs with reclaimable inodes in per-ag radix tree
2010-07-15 11:46 [PATCH 0/3] shrinker fixes for XFS for 2.6.35 Dave Chinner
2010-07-15 11:46 ` [PATCH 1/3] mm: add context argument to shrinker callback Dave Chinner
2010-07-15 11:46 ` [PATCH 2/3] xfs: convert inode shrinker to per-filesystem contexts Dave Chinner
@ 2010-07-15 11:46 ` Dave Chinner
2010-07-15 18:12 ` Christoph Hellwig
2 siblings, 1 reply; 10+ messages in thread
From: Dave Chinner @ 2010-07-15 11:46 UTC (permalink / raw)
To: xfs; +Cc: linux-kernel, linux-fsdevel, linux-mm
From: Dave Chinner <dchinner@redhat.com>
https://bugzilla.kernel.org/show_bug.cgi?id=16348
When the filesystem grows to a large number of allocation groups,
the summing of recalimable inodes gets expensive. In many cases,
most AGs won't have any reclaimable inodes and so we are wasting CPU
time aggregating over these AGs. This is particularly important for
the inode shrinker that gets called frequently under memory
pressure.
To avoid the overhead, track AGs with reclaimable inodes in the
per-ag radix tree so that we can find all the AGs with reclaimable
inodes via a simple gang tag lookup. This involves setting the tag
when the first reclaimable inode is tracked in the AG, and removing
the tag when the last reclaimable inode is removed from the tree.
Then the summation process becomes a loop walking the radix tree
summing AGs with the reclaim tag set.
This significantly reduces the overhead of scanning - a 6400 AG
filesystea now only uses about 25% of a cpu in kswapd while slab
reclaim progresses instead of being permanently stuck at 100% CPU
and making little progress. Clean filesystems filesystems will see
no overhead and the overhead only increases linearly with the number
of dirty AGs.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/linux-2.6/xfs_sync.c | 71 +++++++++++++++++++++++++++++++++++++----
fs/xfs/linux-2.6/xfs_trace.h | 3 ++
2 files changed, 67 insertions(+), 7 deletions(-)
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index f433819..a51a07c 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -144,6 +144,41 @@ restart:
return last_error;
}
+/*
+ * Select the next per-ag structure to iterate during the walk. The reclaim
+ * walk is optimised only to walk AGs with reclaimable inodes in them.
+ */
+static struct xfs_perag *
+xfs_inode_ag_iter_next_pag(
+ struct xfs_mount *mp,
+ xfs_agnumber_t *first,
+ int tag)
+{
+ struct xfs_perag *pag = NULL;
+
+ if (tag == XFS_ICI_RECLAIM_TAG) {
+ int found;
+ int ref;
+
+ spin_lock(&mp->m_perag_lock);
+ found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
+ (void **)&pag, *first, 1, tag);
+ if (found <= 0) {
+ spin_unlock(&mp->m_perag_lock);
+ return NULL;
+ }
+ *first = pag->pag_agno + 1;
+ /* open coded pag reference increment */
+ ref = atomic_inc_return(&pag->pag_ref);
+ spin_unlock(&mp->m_perag_lock);
+ trace_xfs_perag_get_reclaim(mp, pag->pag_agno, ref, _RET_IP_);
+ } else {
+ pag = xfs_perag_get(mp, *first);
+ (*first)++;
+ }
+ return pag;
+}
+
int
xfs_inode_ag_iterator(
struct xfs_mount *mp,
@@ -154,16 +189,15 @@ xfs_inode_ag_iterator(
int exclusive,
int *nr_to_scan)
{
+ struct xfs_perag *pag;
int error = 0;
int last_error = 0;
xfs_agnumber_t ag;
int nr;
nr = nr_to_scan ? *nr_to_scan : INT_MAX;
- for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
- struct xfs_perag *pag;
-
- pag = xfs_perag_get(mp, ag);
+ ag = 0;
+ while ((pag = xfs_inode_ag_iter_next_pag(mp, &ag, tag))) {
error = xfs_inode_ag_walk(mp, pag, execute, flags, tag,
exclusive, &nr);
xfs_perag_put(pag);
@@ -640,6 +674,17 @@ __xfs_inode_set_reclaim_tag(
radix_tree_tag_set(&pag->pag_ici_root,
XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
XFS_ICI_RECLAIM_TAG);
+
+ if (!pag->pag_ici_reclaimable) {
+ /* propagate the reclaim tag up into the perag radix tree */
+ spin_lock(&ip->i_mount->m_perag_lock);
+ radix_tree_tag_set(&ip->i_mount->m_perag_tree,
+ XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+ XFS_ICI_RECLAIM_TAG);
+ spin_unlock(&ip->i_mount->m_perag_lock);
+ trace_xfs_perag_set_reclaim(ip->i_mount, pag->pag_agno,
+ -1, _RET_IP_);
+ }
pag->pag_ici_reclaimable++;
}
@@ -674,6 +719,16 @@ __xfs_inode_clear_reclaim_tag(
radix_tree_tag_clear(&pag->pag_ici_root,
XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
pag->pag_ici_reclaimable--;
+ if (!pag->pag_ici_reclaimable) {
+ /* clear the reclaim tag from the perag radix tree */
+ spin_lock(&ip->i_mount->m_perag_lock);
+ radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
+ XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+ XFS_ICI_RECLAIM_TAG);
+ spin_unlock(&ip->i_mount->m_perag_lock);
+ trace_xfs_perag_clear_reclaim(ip->i_mount, pag->pag_agno,
+ -1, _RET_IP_);
+ }
}
/*
@@ -838,7 +893,7 @@ xfs_reclaim_inode_shrink(
struct xfs_mount *mp;
struct xfs_perag *pag;
xfs_agnumber_t ag;
- int reclaimable = 0;
+ int reclaimable;
mp = container_of(shrink, struct xfs_mount, m_inode_shrink);
if (nr_to_scan) {
@@ -852,8 +907,10 @@ xfs_reclaim_inode_shrink(
return -1;
}
- for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
- pag = xfs_perag_get(mp, ag);
+ reclaimable = 0;
+ ag = 0;
+ while ((pag = xfs_inode_ag_iter_next_pag(mp, &ag,
+ XFS_ICI_RECLAIM_TAG))) {
reclaimable += pag->pag_ici_reclaimable;
xfs_perag_put(pag);
}
diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
index 73d5aa1..3028206 100644
--- a/fs/xfs/linux-2.6/xfs_trace.h
+++ b/fs/xfs/linux-2.6/xfs_trace.h
@@ -124,7 +124,10 @@ DEFINE_EVENT(xfs_perag_class, name, \
unsigned long caller_ip), \
TP_ARGS(mp, agno, refcount, caller_ip))
DEFINE_PERAG_REF_EVENT(xfs_perag_get);
+DEFINE_PERAG_REF_EVENT(xfs_perag_get_reclaim);
DEFINE_PERAG_REF_EVENT(xfs_perag_put);
+DEFINE_PERAG_REF_EVENT(xfs_perag_set_reclaim);
+DEFINE_PERAG_REF_EVENT(xfs_perag_clear_reclaim);
TRACE_EVENT(xfs_attr_list_node_descend,
TP_PROTO(struct xfs_attr_list_context *ctx,
--
1.7.1
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