Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756321AbXKVAd7 (ORCPT ); Wed, 21 Nov 2007 19:33:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753535AbXKVAdv (ORCPT ); Wed, 21 Nov 2007 19:33:51 -0500 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:50681 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753403AbXKVAdv (ORCPT ); Wed, 21 Nov 2007 19:33:51 -0500 Date: Thu, 22 Nov 2007 11:33:39 +1100 From: David Chinner To: xfs-oss Cc: lkml Subject: [PATCH 2/9]: Reduce Log I/O latency Message-ID: <20071122003339.GH114266761@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3103 Lines: 71 Reduce log I/O latency To ensure that log I/O is issued as the highest priority I/O, set the I/O priority of the log I/O to the highest possible. This will ensure that log I/O is not held up behind bulk data or other metadata I/O as delaying log I/O can pause the entire transaction subsystem. Introduce a new buffer flag to allow us to tag the log buffers so we can discrimiate when issuing the I/O. Signed-off-by: Dave Chinner --- fs/xfs/linux-2.6/xfs_buf.c | 3 +++ fs/xfs/linux-2.6/xfs_buf.h | 5 ++++- fs/xfs/xfs_log.c | 2 ++ 3 files changed, 9 insertions(+), 1 deletion(-) Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_buf.c =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_buf.c 2007-11-22 10:47:21.937396362 +1100 +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_buf.c 2007-11-22 10:53:11.556186722 +1100 @@ -1255,6 +1255,9 @@ next_chunk: submit_io: if (likely(bio->bi_size)) { + /* log I/O should not be delayed by anything. */ + if (bp->b_flags & XBF_LOG_BUFFER) + bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 0)); submit_bio(rw, bio); if (size) goto next_chunk; Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_buf.h =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_buf.h 2007-11-22 10:47:21.945395328 +1100 +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_buf.h 2007-11-22 10:53:11.556186722 +1100 @@ -53,7 +53,8 @@ typedef enum { XBF_DELWRI = (1 << 6), /* buffer has dirty pages */ XBF_STALE = (1 << 7), /* buffer has been staled, do not find it */ XBF_FS_MANAGED = (1 << 8), /* filesystem controls freeing memory */ - XBF_ORDERED = (1 << 11), /* use ordered writes */ + XBF_LOG_BUFFER = (1 << 9), /* Buffer issued by the log */ + XBF_ORDERED = (1 << 11), /* use ordered writes */ XBF_READ_AHEAD = (1 << 12), /* asynchronous read-ahead */ /* flags used only as arguments to access routines */ @@ -340,6 +341,8 @@ extern void xfs_buf_trace(xfs_buf_t *, c #define XFS_BUF_TARGET(bp) ((bp)->b_target) #define XFS_BUFTARG_NAME(target) xfs_buf_target_name(target) +#define XFS_BUF_SET_LOGBUF(bp) ((bp)->b_flags |= XBF_LOG_BUFFER) + static inline int xfs_bawrite(void *mp, xfs_buf_t *bp) { bp->b_fspriv3 = mp; Index: 2.6.x-xfs-new/fs/xfs/xfs_log.c =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/xfs_log.c 2007-11-22 10:47:21.945395328 +1100 +++ 2.6.x-xfs-new/fs/xfs/xfs_log.c 2007-11-22 10:53:11.556186722 +1100 @@ -1443,6 +1443,8 @@ xlog_sync(xlog_t *log, XFS_BUF_ZEROFLAGS(bp); XFS_BUF_BUSY(bp); XFS_BUF_ASYNC(bp); + XFS_BUF_SET_LOGBUF(bp); + /* * Do an ordered write for the log block. * Its unnecessary to flush the first split block in the log wrap case. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/