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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 664acdb..36a3091 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -181,11 +181,12 @@
*/
void inode_wb_list_del(struct inode *inode)
{
- spin_lock(&inode_wb_list_lock);
- list_del_init(&inode->i_wb_list);
- spin_unlock(&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(&bdi->wb.list_lock);
+}
/*
* Redirty an inode: set its when-it-was dirtied timestamp and move it to the
@@ -196,11 +197,9 @@
* 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 @@
/*
* 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 @@
{
/*
* Prevent speculative execution through
- * spin_unlock(&inode_wb_list_lock);
+ * spin_unlock(&wb->list_lock);
*/
smp_mb();
@@ -302,7 +299,7 @@
*/
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 @@
/*
* 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 @@
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 @@
* 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 @@
* 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 @@
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 @@
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 @@
/*
* 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 @@
* 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 @@
* 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 @@
* 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 @@
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 @@
__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 @@
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 @@
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 @@
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 @@
{
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 @@
* 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 @@
}
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 @@
*/
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 @@
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 @@
*/
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);