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Btrfs: Wait for async bio submissions to make some progress at queue time

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Before, the btrfs bdi congestion function was used to test for too many
async bios.  This keeps that check to throttle pdflush, but also
adds a check while queuing bios.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2008-08-20 13:39:41 -04:00
parent 4d1b5fb4d7
commit b64a2851ba
4 changed files with 27 additions and 10 deletions
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18
fs/btrfs/volumes.c
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@ -138,12 +138,18 @@ int run_scheduled_bios(struct btrfs_device *device)
{
struct bio *pending;
struct backing_dev_info *bdi;
struct btrfs_fs_info *fs_info;
struct bio *tail;
struct bio *cur;
int again = 0;
unsigned long num_run = 0;
unsigned long limit;
bdi = device->bdev->bd_inode->i_mapping->backing_dev_info;
fs_info = device->dev_root->fs_info;
limit = btrfs_async_submit_limit(fs_info);
limit = limit * 2 / 3;
loop:
spin_lock(&device->io_lock);
@ -179,7 +185,11 @@ loop:
cur = pending;
pending = pending->bi_next;
cur->bi_next = NULL;
atomic_dec(&device->dev_root->fs_info->nr_async_bios);
atomic_dec(&fs_info->nr_async_bios);
if (atomic_read(&fs_info->nr_async_bios) < limit &&
waitqueue_active(&fs_info->async_submit_wait))
wake_up(&fs_info->async_submit_wait);
BUG_ON(atomic_read(&cur->bi_cnt) == 0);
bio_get(cur);
@ -2135,6 +2145,7 @@ int schedule_bio(struct btrfs_root *root, struct btrfs_device *device,
int rw, struct bio *bio)
{
int should_queue = 1;
unsigned long limit;
/* don't bother with additional async steps for reads, right now */
if (!(rw & (1 << BIO_RW))) {
@ -2171,6 +2182,11 @@ int schedule_bio(struct btrfs_root *root, struct btrfs_device *device,
if (should_queue)
btrfs_queue_worker(&root->fs_info->submit_workers,
&device->work);
limit = btrfs_async_submit_limit(root->fs_info);
wait_event_timeout(root->fs_info->async_submit_wait,
(atomic_read(&root->fs_info->nr_async_bios) < limit),
HZ/10);
return 0;
}