Commit b29c70f5 authored by Brian Foster's avatar Brian Foster Committed by Dave Chinner
Browse files

xfs: split metadata and log buffer completion to separate workqueues 



XFS traditionally sends all buffer I/O completion work to a single
workqueue. This includes metadata buffer completion and log buffer
completion. The log buffer completion requires a high priority queue to
prevent stalls due to log forces getting stuck behind other queued work.

Rather than continue to prioritize all buffer I/O completion due to the
needs of log completion, split log buffer completion off to
m_log_workqueue and move the high priority flag from m_buf_workqueue to
m_log_workqueue.

Add a b_ioend_wq wq pointer to xfs_buf to allow completion workqueue
customization on a per-buffer basis. Initialize b_ioend_wq to
m_buf_workqueue by default in the generic buffer I/O submission path.
Finally, override the default wq with the high priority m_log_workqueue
in the log buffer I/O submission path.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent 32296f86

fs/xfs/xfs_buf.c

+10 −3
Original line number Diff line number Diff line
@@ -1041,7 +1041,7 @@ xfs_buf_ioend_work( 
	struct work_struct	*work)

{

	struct xfs_buf		*bp =

		container_of(work, xfs_buf_t, b_iodone_work);

		container_of(work, xfs_buf_t, b_ioend_work);



	xfs_buf_ioend(bp);

}
@@ -1050,8 +1050,8 @@ void 
xfs_buf_ioend_async(

	struct xfs_buf	*bp)

{

	INIT_WORK(&bp->b_iodone_work, xfs_buf_ioend_work);

	queue_work(bp->b_target->bt_mount->m_buf_workqueue, &bp->b_iodone_work);

	INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);

	queue_work(bp->b_ioend_wq, &bp->b_ioend_work);

}



void
@@ -1220,6 +1220,13 @@ _xfs_buf_ioapply( 
	 */

	bp->b_error = 0;



	/*

	 * Initialize the I/O completion workqueue if we haven't yet or the

	 * submitter has not opted to specify a custom one.

	 */

	if (!bp->b_ioend_wq)

		bp->b_ioend_wq = bp->b_target->bt_mount->m_buf_workqueue;



	if (bp->b_flags & XBF_WRITE) {

		if (bp->b_flags & XBF_SYNCIO)

			rw = WRITE_SYNC;

fs/xfs/xfs_buf.h

+2 −1
Original line number Diff line number Diff line
@@ -164,7 +164,8 @@ typedef struct xfs_buf { 
	struct xfs_perag	*b_pag;		/* contains rbtree root */

	xfs_buftarg_t		*b_target;	/* buffer target (device) */

	void			*b_addr;	/* virtual address of buffer */

	struct work_struct	b_iodone_work;

	struct work_struct	b_ioend_work;

	struct workqueue_struct	*b_ioend_wq;	/* I/O completion wq */

	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */

	struct completion	b_iowait;	/* queue for I/O waiters */

	void			*b_fspriv;

fs/xfs/xfs_log.c

+4 −0
Original line number Diff line number Diff line
@@ -1808,6 +1808,8 @@ xlog_sync( 
	XFS_BUF_ZEROFLAGS(bp);

	XFS_BUF_ASYNC(bp);

	bp->b_flags |= XBF_SYNCIO;

	/* use high priority completion wq */

	bp->b_ioend_wq = log->l_mp->m_log_workqueue;



	if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) {

		bp->b_flags |= XBF_FUA;
@@ -1856,6 +1858,8 @@ xlog_sync( 
		bp->b_flags |= XBF_SYNCIO;

		if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)

			bp->b_flags |= XBF_FUA;

		/* use high priority completion wq */

		bp->b_ioend_wq = log->l_mp->m_log_workqueue;



		ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);

		ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);

fs/xfs/xfs_super.c

+2 −3
Original line number Diff line number Diff line
@@ -842,8 +842,7 @@ xfs_init_mount_workqueues( 
	struct xfs_mount	*mp)

{

	mp->m_buf_workqueue = alloc_workqueue("xfs-buf/%s",

			WQ_MEM_RECLAIM|WQ_HIGHPRI|WQ_FREEZABLE, 1,

			mp->m_fsname);

			WQ_MEM_RECLAIM|WQ_FREEZABLE, 1, mp->m_fsname);

	if (!mp->m_buf_workqueue)

		goto out;
@@ -868,7 +867,7 @@ xfs_init_mount_workqueues( 
		goto out_destroy_cil;



	mp->m_log_workqueue = alloc_workqueue("xfs-log/%s",

			WQ_FREEZABLE, 0, mp->m_fsname);

			WQ_FREEZABLE|WQ_HIGHPRI, 0, mp->m_fsname);

	if (!mp->m_log_workqueue)

		goto out_destroy_reclaim;

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