xfs
[Top] [All Lists]

Re: [PATCH v2] xfs: improve metadata I/O merging in the elevator

To: xfs@xxxxxxxxxxx
Subject: Re: [PATCH v2] xfs: improve metadata I/O merging in the elevator
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue, 24 Nov 2009 13:03:15 -0500
In-reply-to: <20091112190930.GB32110@xxxxxxxxxxxxx>
References: <20091112190930.GB32110@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.19 (2009-01-05)
From: Dave Chinner <dgc@xxxxxxx>

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: Dave Chinner <dgc@xxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: xfs/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_buf.c 2009-11-16 12:03:21.940253900 +0100
+++ xfs/fs/xfs/linux-2.6/xfs_buf.c      2009-11-16 12:05:54.224256517 +0100
@@ -1177,10 +1177,14 @@ _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;
Index: xfs/fs/xfs/linux-2.6/xfs_buf.h
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_buf.h 2009-11-16 12:03:21.945261731 +0100
+++ xfs/fs/xfs/linux-2.6/xfs_buf.h      2009-11-16 12:03:23.796003934 +0100
@@ -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                      */
Index: xfs/fs/xfs/xfs_log.c
===================================================================
--- xfs.orig/fs/xfs/xfs_log.c   2009-11-16 12:03:21.952261854 +0100
+++ xfs/fs/xfs/xfs_log.c        2009-11-16 12:03:23.798003071 +0100
@@ -1524,6 +1524,7 @@ 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.
@@ -1561,6 +1562,7 @@ 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);
Index: xfs/include/linux/fs.h
===================================================================
--- xfs.orig/include/linux/fs.h 2009-11-16 12:04:49.799002997 +0100
+++ xfs/include/linux/fs.h      2009-11-16 12:05:10.130255677 +0100
@@ -151,6 +151,7 @@ struct inodes_stat_t {
 #define READ_META      (READ | (1 << BIO_RW_META))
 #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_META     (WRITE | (1 << BIO_RW_META))
 #define WRITE_ODIRECT  (WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
 #define SWRITE_SYNC_PLUG       \
                        (SWRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))

<Prev in Thread] Current Thread [Next in Thread>