[PATCH 3/4] jbd: yield the device queue when waiting for commits

From: Jeff Moyer
Date: Tue May 18 2010 - 14:20:51 EST


This patch gets CFQ back in line with deadline for iozone runs, especially
those testing small files + fsync timings.

Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
---
fs/jbd/journal.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index bd224ee..267108f 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -36,6 +36,7 @@
#include <linux/poison.h>
#include <linux/proc_fs.h>
#include <linux/debugfs.h>
+#include <linux/blkdev.h>

#include <asm/uaccess.h>
#include <asm/page.h>
@@ -549,6 +550,11 @@ int log_wait_commit(journal_t *journal, tid_t tid)
while (tid_gt(tid, journal->j_commit_sequence)) {
jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
tid, journal->j_commit_sequence);
+ /*
+ * Give up our I/O scheduler time slice to allow the journal
+ * thread to issue I/O.
+ */
+ blk_yield(journal->j_dev->bd_disk->queue, journal->j_task);
wake_up(&journal->j_wait_commit);
spin_unlock(&journal->j_state_lock);
wait_event(journal->j_wait_done_commit,
--
1.6.5.2

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