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Btrfs: run the backing dev more often in the submit_bio helper

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The submit_bio helper thread can decide to loop back around to
service more bios.  This commit forces it to unplug first, which helps
reduce the latency seen by submitters.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2010-03-10 15:33:32 -05:00
parent 4849f01d15
commit 51684082b1
1 changed files with 10 additions and 10 deletions
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20
fs/btrfs/volumes.c
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@@ -325,16 +325,6 @@ loop_lock:
num_sync_run = 0; num_sync_run = 0;
blk_run_backing_dev(bdi, NULL); blk_run_backing_dev(bdi, NULL);
} }
cond_resched();
if (again)
goto loop;
spin_lock(&device->io_lock);
if (device->pending_bios.head || device->pending_sync_bios.head)
goto loop_lock;
spin_unlock(&device->io_lock);
/* /*
* IO has already been through a long path to get here. Checksumming, * IO has already been through a long path to get here. Checksumming,
* async helper threads, perhaps compression. We've done a pretty * async helper threads, perhaps compression. We've done a pretty
@@ -346,6 +336,16 @@ loop_lock:
* cared about found its way down here. * cared about found its way down here.
*/ */
blk_run_backing_dev(bdi, NULL); blk_run_backing_dev(bdi, NULL);
cond_resched();
if (again)
goto loop;
spin_lock(&device->io_lock);
if (device->pending_bios.head || device->pending_sync_bios.head)
goto loop_lock;
spin_unlock(&device->io_lock);
done: done:
return 0; return 0;
} }