Commit f758eeab authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Wu Fengguang

writeback: split inode_wb_list_lock into bdi_writeback.list_lock

Split the global inode_wb_list_lock into a per-bdi_writeback list_lock,
as it's currently the most contended lock in the system for metadata
heavy workloads.  It won't help for single-filesystem workloads for
which we'll need the I/O-less balance_dirty_pages, but at least we
can dedicate a cpu to spinning on each bdi now for larger systems.

Based on earlier patches from Nick Piggin and Dave Chinner.

It reduces lock contentions to 1/4 in this test case:
10 HDD JBOD, 100 dd on each disk, XFS, 6GB ram

lock_stat version 0.3
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                              class name    con-bounces    contentions   waittime-min   waittime-max waittime-total    acq-bounces   acquisitions   holdtime-min   holdtime-max holdtime-total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
vanilla 2.6.39-rc3:
                      inode_wb_list_lock:         42590          44433           0.12         147.74      144127.35         252274         886792           0.08         121.34      917211.23
                      ------------------
                      inode_wb_list_lock              2          [<ffffffff81165da5>] bdev_inode_switch_bdi+0x29/0x85
                      inode_wb_list_lock             34          [<ffffffff8115bd0b>] inode_wb_list_del+0x22/0x49
                      inode_wb_list_lock          12893          [<ffffffff8115bb53>] __mark_inode_dirty+0x170/0x1d0
                      inode_wb_list_lock          10702          [<ffffffff8115afef>] writeback_single_inode+0x16d/0x20a
                      ------------------
                      inode_wb_list_lock              2          [<ffffffff81165da5>] bdev_inode_switch_bdi+0x29/0x85
                      inode_wb_list_lock             19          [<ffffffff8115bd0b>] inode_wb_list_del+0x22/0x49
                      inode_wb_list_lock           5550          [<ffffffff8115bb53>] __mark_inode_dirty+0x170/0x1d0
                      inode_wb_list_lock           8511          [<ffffffff8115b4ad>] writeback_sb_inodes+0x10f/0x157

2.6.39-rc3 + patch:
                &(&wb->list_lock)->rlock:         11383          11657           0.14         151.69       40429.51          90825         527918           0.11         145.90      556843.37
                ------------------------
                &(&wb->list_lock)->rlock             10          [<ffffffff8115b189>] inode_wb_list_del+0x5f/0x86
                &(&wb->list_lock)->rlock           1493          [<ffffffff8115b1ed>] writeback_inodes_wb+0x3d/0x150
                &(&wb->list_lock)->rlock           3652          [<ffffffff8115a8e9>] writeback_sb_inodes+0x123/0x16f
                &(&wb->list_lock)->rlock           1412          [<ffffffff8115a38e>] writeback_single_inode+0x17f/0x223
                ------------------------
                &(&wb->list_lock)->rlock              3          [<ffffffff8110b5af>] bdi_lock_two+0x46/0x4b
                &(&wb->list_lock)->rlock              6          [<ffffffff8115b189>] inode_wb_list_del+0x5f/0x86
                &(&wb->list_lock)->rlock           2061          [<ffffffff8115af97>] __mark_inode_dirty+0x173/0x1cf
                &(&wb->list_lock)->rlock           2629          [<ffffffff8115a8e9>] writeback_sb_inodes+0x123/0x16f

hughd@google.com: fix recursive lock when bdi_lock_two() is called with new the same as old
akpm@linux-foundation.org: cleanup bdev_inode_switch_bdi() comment
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
parent 424b351f
......@@ -44,24 +44,28 @@ inline struct block_device *I_BDEV(struct inode *inode)
{
return &BDEV_I(inode)->bdev;
}
EXPORT_SYMBOL(I_BDEV);
/*
* move the inode from it's current bdi to the a new bdi. if the inode is dirty
* we need to move it onto the dirty list of @dst so that the inode is always
* on the right list.
* Move the inode from its current bdi to a new bdi. If the inode is dirty we
* need to move it onto the dirty list of @dst so that the inode is always on
* the right list.
*/
static void bdev_inode_switch_bdi(struct inode *inode,
struct backing_dev_info *dst)
{
spin_lock(&inode_wb_list_lock);
struct backing_dev_info *old = inode->i_data.backing_dev_info;
if (unlikely(dst == old)) /* deadlock avoidance */
return;
bdi_lock_two(&old->wb, &dst->wb);
spin_lock(&inode->i_lock);
inode->i_data.backing_dev_info = dst;
if (inode->i_state & I_DIRTY)
list_move(&inode->i_wb_list, &dst->wb.b_dirty);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&old->wb.list_lock);
spin_unlock(&dst->wb.list_lock);
}
static sector_t max_block(struct block_device *bdev)
......
......@@ -181,12 +181,13 @@ void bdi_start_background_writeback(struct backing_dev_info *bdi)
*/
void inode_wb_list_del(struct inode *inode)
{
spin_lock(&inode_wb_list_lock);
struct backing_dev_info *bdi = inode_to_bdi(inode);
spin_lock(&bdi->wb.list_lock);
list_del_init(&inode->i_wb_list);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&bdi->wb.list_lock);
}
/*
* Redirty an inode: set its when-it-was dirtied timestamp and move it to the
* furthest end of its superblock's dirty-inode list.
......@@ -196,11 +197,9 @@ void inode_wb_list_del(struct inode *inode)
* the case then the inode must have been redirtied while it was being written
* out and we don't reset its dirtied_when.
*/
static void redirty_tail(struct inode *inode)
static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
{
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
assert_spin_locked(&inode_wb_list_lock);
assert_spin_locked(&wb->list_lock);
if (!list_empty(&wb->b_dirty)) {
struct inode *tail;
......@@ -214,11 +213,9 @@ static void redirty_tail(struct inode *inode)
/*
* requeue inode for re-scanning after bdi->b_io list is exhausted.
*/
static void requeue_io(struct inode *inode)
static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
{
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
assert_spin_locked(&inode_wb_list_lock);
assert_spin_locked(&wb->list_lock);
list_move(&inode->i_wb_list, &wb->b_more_io);
}
......@@ -226,7 +223,7 @@ static void inode_sync_complete(struct inode *inode)
{
/*
* Prevent speculative execution through
* spin_unlock(&inode_wb_list_lock);
* spin_unlock(&wb->list_lock);
*/
smp_mb();
......@@ -302,7 +299,7 @@ static void move_expired_inodes(struct list_head *delaying_queue,
*/
static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
{
assert_spin_locked(&inode_wb_list_lock);
assert_spin_locked(&wb->list_lock);
list_splice_init(&wb->b_more_io, &wb->b_io);
move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
}
......@@ -317,7 +314,8 @@ static int write_inode(struct inode *inode, struct writeback_control *wbc)
/*
* Wait for writeback on an inode to complete.
*/
static void inode_wait_for_writeback(struct inode *inode)
static void inode_wait_for_writeback(struct inode *inode,
struct bdi_writeback *wb)
{
DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
wait_queue_head_t *wqh;
......@@ -325,15 +323,15 @@ static void inode_wait_for_writeback(struct inode *inode)
wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
while (inode->i_state & I_SYNC) {
spin_unlock(&inode->i_lock);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
__wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE);
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
spin_lock(&inode->i_lock);
}
}
/*
* Write out an inode's dirty pages. Called under inode_wb_list_lock and
* Write out an inode's dirty pages. Called under wb->list_lock and
* inode->i_lock. Either the caller has an active reference on the inode or
* the inode has I_WILL_FREE set.
*
......@@ -344,13 +342,14 @@ static void inode_wait_for_writeback(struct inode *inode)
* livelocks, etc.
*/
static int
writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
struct writeback_control *wbc)
{
struct address_space *mapping = inode->i_mapping;
unsigned dirty;
int ret;
assert_spin_locked(&inode_wb_list_lock);
assert_spin_locked(&wb->list_lock);
assert_spin_locked(&inode->i_lock);
if (!atomic_read(&inode->i_count))
......@@ -368,14 +367,14 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* completed a full scan of b_io.
*/
if (wbc->sync_mode != WB_SYNC_ALL) {
requeue_io(inode);
requeue_io(inode, wb);
return 0;
}
/*
* It's a data-integrity sync. We must wait.
*/
inode_wait_for_writeback(inode);
inode_wait_for_writeback(inode, wb);
}
BUG_ON(inode->i_state & I_SYNC);
......@@ -384,7 +383,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
inode->i_state |= I_SYNC;
inode->i_state &= ~I_DIRTY_PAGES;
spin_unlock(&inode->i_lock);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
ret = do_writepages(mapping, wbc);
......@@ -415,7 +414,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
ret = err;
}
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
spin_lock(&inode->i_lock);
inode->i_state &= ~I_SYNC;
if (!(inode->i_state & I_FREEING)) {
......@@ -438,7 +437,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
/*
* slice used up: queue for next turn
*/
requeue_io(inode);
requeue_io(inode, wb);
} else {
/*
* Writeback blocked by something other than
......@@ -447,7 +446,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* retrying writeback of the dirty page/inode
* that cannot be performed immediately.
*/
redirty_tail(inode);
redirty_tail(inode, wb);
}
} else if (inode->i_state & I_DIRTY) {
/*
......@@ -456,7 +455,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* submission or metadata updates after data IO
* completion.
*/
redirty_tail(inode);
redirty_tail(inode, wb);
} else {
/*
* The inode is clean. At this point we either have
......@@ -521,7 +520,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
* superblock, move all inodes not belonging
* to it back onto the dirty list.
*/
redirty_tail(inode);
redirty_tail(inode, wb);
continue;
}
......@@ -541,7 +540,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
spin_unlock(&inode->i_lock);
requeue_io(inode);
requeue_io(inode, wb);
continue;
}
......@@ -557,19 +556,19 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
__iget(inode);
pages_skipped = wbc->pages_skipped;
writeback_single_inode(inode, wbc);
writeback_single_inode(inode, wb, wbc);
if (wbc->pages_skipped != pages_skipped) {
/*
* writeback is not making progress due to locked
* buffers. Skip this inode for now.
*/
redirty_tail(inode);
redirty_tail(inode, wb);
}
spin_unlock(&inode->i_lock);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
iput(inode);
cond_resched();
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
if (wbc->nr_to_write <= 0) {
wbc->more_io = 1;
return 1;
......@@ -588,7 +587,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
if (!wbc->wb_start)
wbc->wb_start = jiffies; /* livelock avoidance */
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
if (list_empty(&wb->b_io))
queue_io(wb, wbc->older_than_this);
......@@ -598,7 +597,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
struct super_block *sb = inode->i_sb;
if (!pin_sb_for_writeback(sb)) {
requeue_io(inode);
requeue_io(inode, wb);
continue;
}
ret = writeback_sb_inodes(sb, wb, wbc, false);
......@@ -607,7 +606,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
if (ret)
break;
}
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
/* Leave any unwritten inodes on b_io */
}
......@@ -616,11 +615,11 @@ static void __writeback_inodes_sb(struct super_block *sb,
{
WARN_ON(!rwsem_is_locked(&sb->s_umount));
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
if (list_empty(&wb->b_io))
queue_io(wb, wbc->older_than_this);
writeback_sb_inodes(sb, wb, wbc, true);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
}
/*
......@@ -762,15 +761,15 @@ static long wb_writeback(struct bdi_writeback *wb,
* become available for writeback. Otherwise
* we'll just busyloop.
*/
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
if (!list_empty(&wb->b_more_io)) {
inode = wb_inode(wb->b_more_io.prev);
trace_wbc_writeback_wait(&wbc, wb->bdi);
spin_lock(&inode->i_lock);
inode_wait_for_writeback(inode);
inode_wait_for_writeback(inode, wb);
spin_unlock(&inode->i_lock);
}
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
}
return wrote;
......@@ -1104,10 +1103,10 @@ void __mark_inode_dirty(struct inode *inode, int flags)
}
spin_unlock(&inode->i_lock);
spin_lock(&inode_wb_list_lock);
spin_lock(&bdi->wb.list_lock);
inode->dirtied_when = jiffies;
list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&bdi->wb.list_lock);
if (wakeup_bdi)
bdi_wakeup_thread_delayed(bdi);
......@@ -1309,6 +1308,7 @@ EXPORT_SYMBOL(sync_inodes_sb);
*/
int write_inode_now(struct inode *inode, int sync)
{
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
int ret;
struct writeback_control wbc = {
.nr_to_write = LONG_MAX,
......@@ -1321,11 +1321,11 @@ int write_inode_now(struct inode *inode, int sync)
wbc.nr_to_write = 0;
might_sleep();
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
spin_lock(&inode->i_lock);
ret = writeback_single_inode(inode, &wbc);
ret = writeback_single_inode(inode, wb, &wbc);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
if (sync)
inode_sync_wait(inode);
return ret;
......@@ -1345,13 +1345,14 @@ EXPORT_SYMBOL(write_inode_now);
*/
int sync_inode(struct inode *inode, struct writeback_control *wbc)
{
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
int ret;
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
spin_lock(&inode->i_lock);
ret = writeback_single_inode(inode, wbc);
ret = writeback_single_inode(inode, wb, wbc);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
return ret;
}
EXPORT_SYMBOL(sync_inode);
......
......@@ -37,7 +37,7 @@
* inode_lru, inode->i_lru
* inode_sb_list_lock protects:
* sb->s_inodes, inode->i_sb_list
* inode_wb_list_lock protects:
* bdi->wb.list_lock protects:
* bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list
* inode_hash_lock protects:
* inode_hashtable, inode->i_hash
......@@ -48,7 +48,7 @@
* inode->i_lock
* inode_lru_lock
*
* inode_wb_list_lock
* bdi->wb.list_lock
* inode->i_lock
*
* inode_hash_lock
......@@ -68,7 +68,6 @@ static LIST_HEAD(inode_lru);
static DEFINE_SPINLOCK(inode_lru_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_wb_list_lock);
/*
* iprune_sem provides exclusion between the icache shrinking and the
......
......@@ -57,6 +57,7 @@ struct bdi_writeback {
struct list_head b_dirty; /* dirty inodes */
struct list_head b_io; /* parked for writeback */
struct list_head b_more_io; /* parked for more writeback */
spinlock_t list_lock; /* protects the b_* lists */
};
struct backing_dev_info {
......@@ -106,6 +107,7 @@ int bdi_writeback_thread(void *data);
int bdi_has_dirty_io(struct backing_dev_info *bdi);
void bdi_arm_supers_timer(void);
void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
extern spinlock_t bdi_lock;
extern struct list_head bdi_list;
......
......@@ -9,8 +9,6 @@
struct backing_dev_info;
extern spinlock_t inode_wb_list_lock;
/*
* fs/fs-writeback.c
*/
......
......@@ -45,6 +45,17 @@ static struct timer_list sync_supers_timer;
static int bdi_sync_supers(void *);
static void sync_supers_timer_fn(unsigned long);
void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
{
if (wb1 < wb2) {
spin_lock(&wb1->list_lock);
spin_lock_nested(&wb2->list_lock, 1);
} else {
spin_lock(&wb2->list_lock);
spin_lock_nested(&wb1->list_lock, 1);
}
}
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/seq_file.h>
......@@ -67,14 +78,14 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
struct inode *inode;
nr_dirty = nr_io = nr_more_io = 0;
spin_lock(&inode_wb_list_lock);
spin_lock(&wb->list_lock);
list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
nr_dirty++;
list_for_each_entry(inode, &wb->b_io, i_wb_list)
nr_io++;
list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
nr_more_io++;
spin_unlock(&inode_wb_list_lock);
spin_unlock(&wb->list_lock);
global_dirty_limits(&background_thresh, &dirty_thresh);
bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
......@@ -628,6 +639,7 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
INIT_LIST_HEAD(&wb->b_dirty);
INIT_LIST_HEAD(&wb->b_io);
INIT_LIST_HEAD(&wb->b_more_io);
spin_lock_init(&wb->list_lock);
setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi);
}
......@@ -676,11 +688,12 @@ void bdi_destroy(struct backing_dev_info *bdi)
if (bdi_has_dirty_io(bdi)) {
struct bdi_writeback *dst = &default_backing_dev_info.wb;
spin_lock(&inode_wb_list_lock);
bdi_lock_two(&bdi->wb, dst);
list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
list_splice(&bdi->wb.b_io, &dst->b_io);
list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
spin_unlock(&inode_wb_list_lock);
spin_unlock(&bdi->wb.list_lock);
spin_unlock(&dst->list_lock);
}
bdi_unregister(bdi);
......
......@@ -81,7 +81,7 @@
* ->i_mutex
* ->i_alloc_sem (various)
*
* inode_wb_list_lock
* bdi->wb.list_lock
* sb_lock (fs/fs-writeback.c)
* ->mapping->tree_lock (__sync_single_inode)
*
......@@ -99,9 +99,9 @@
* ->zone.lru_lock (check_pte_range->isolate_lru_page)
* ->private_lock (page_remove_rmap->set_page_dirty)
* ->tree_lock (page_remove_rmap->set_page_dirty)
* inode_wb_list_lock (page_remove_rmap->set_page_dirty)
* bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
* ->inode->i_lock (page_remove_rmap->set_page_dirty)
* inode_wb_list_lock (zap_pte_range->set_page_dirty)
* bdi.wb->list_lock (zap_pte_range->set_page_dirty)
* ->inode->i_lock (zap_pte_range->set_page_dirty)
* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
*
......
......@@ -32,11 +32,11 @@
* mmlist_lock (in mmput, drain_mmlist and others)
* mapping->private_lock (in __set_page_dirty_buffers)
* inode->i_lock (in set_page_dirty's __mark_inode_dirty)
* inode_wb_list_lock (in set_page_dirty's __mark_inode_dirty)
* bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
* sb_lock (within inode_lock in fs/fs-writeback.c)
* mapping->tree_lock (widely used, in set_page_dirty,
* in arch-dependent flush_dcache_mmap_lock,
* within inode_wb_list_lock in __sync_single_inode)
* within bdi.wb->list_lock in __sync_single_inode)
*
* (code doesn't rely on that order so it could be switched around)
* ->tasklist_lock
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment