Commit 2ee1abad authored by Dave Chinner's avatar Dave Chinner Committed by Alex Elder
Browse files

xfs: improve metadata I/O merging in the elevator 



Change all async metadata buffers to use [READ|WRITE]_META I/O types
so that the I/O doesn't get issued immediately. This allows merging of
adjacent metadata requests but still prioritises them over bulk data.
This shows a 10-15% improvement in sequential create speed of small
files.

Don't include the log buffers in this classification - leave them as
sync types so they are issued immediately.

Signed-off-by: default avatarDave Chinner <dgc@sgi.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
parent b44b1126

fs/xfs/linux-2.6/xfs_buf.c

+5 −1
Original line number Diff line number Diff line
@@ -1149,10 +1149,14 @@ _xfs_buf_ioapply( 
	if (bp->b_flags & XBF_ORDERED) {

		ASSERT(!(bp->b_flags & XBF_READ));

		rw = WRITE_BARRIER;

	} else if (bp->b_flags & _XBF_RUN_QUEUES) {

	} else if (bp->b_flags & XBF_LOG_BUFFER) {

		ASSERT(!(bp->b_flags & XBF_READ_AHEAD));

		bp->b_flags &= ~_XBF_RUN_QUEUES;

		rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;

	} else if (bp->b_flags & _XBF_RUN_QUEUES) {

		ASSERT(!(bp->b_flags & XBF_READ_AHEAD));

		bp->b_flags &= ~_XBF_RUN_QUEUES;

		rw = (bp->b_flags & XBF_WRITE) ? WRITE_META : READ_META;

	} else {

		rw = (bp->b_flags & XBF_WRITE) ? WRITE :

		     (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;

fs/xfs/linux-2.6/xfs_buf.h

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ typedef enum { 
	XBF_FS_MANAGED = (1 << 8),  /* filesystem controls freeing memory  */

 	XBF_ORDERED = (1 << 11),    /* use ordered writes		   */

	XBF_READ_AHEAD = (1 << 12), /* asynchronous read-ahead		   */

	XBF_LOG_BUFFER = (1 << 13), /* this is a buffer used for the log   */



	/* flags used only as arguments to access routines */

	XBF_LOCK = (1 << 14),       /* lock requested			   */

fs/xfs/xfs_log.c

+2 −0
Original line number Diff line number Diff line
@@ -1441,6 +1441,7 @@ xlog_sync(xlog_t *log, 
	XFS_BUF_ZEROFLAGS(bp);

	XFS_BUF_BUSY(bp);

	XFS_BUF_ASYNC(bp);

	bp->b_flags |= XBF_LOG_BUFFER;

	/*

	 * Do an ordered write for the log block.

	 * Its unnecessary to flush the first split block in the log wrap case.
@@ -1478,6 +1479,7 @@ xlog_sync(xlog_t *log, 
		XFS_BUF_ZEROFLAGS(bp);

		XFS_BUF_BUSY(bp);

		XFS_BUF_ASYNC(bp);

		bp->b_flags |= XBF_LOG_BUFFER;

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

			XFS_BUF_ORDERED(bp);

		dptr = XFS_BUF_PTR(bp);

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -152,6 +152,7 @@ struct inodes_stat_t { 
#define WRITE_SYNC_PLUG	(WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))

#define WRITE_SYNC	(WRITE_SYNC_PLUG | (1 << BIO_RW_UNPLUG))

#define WRITE_ODIRECT_PLUG	(WRITE | (1 << BIO_RW_SYNCIO))

#define WRITE_META	(WRITE | (1 << BIO_RW_META))

#define SWRITE_SYNC_PLUG	\

			(SWRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))

#define SWRITE_SYNC	(SWRITE_SYNC_PLUG | (1 << BIO_RW_UNPLUG))

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