From: Theodore Tso Subject: [PATCH] block_write_full_page: switch synchronous writes to use WRITE_SYNC_PLUG Date: Tue, 7 Apr 2009 18:19:33 -0400 Message-ID: <20090407221933.GB7031@mit.edu> References: <1238185471-31152-1-git-send-email-tytso@mit.edu> <1238185471-31152-2-git-send-email-tytso@mit.edu> <20090406232141.ebdb426a.akpm@linux-foundation.org> <20090406235052.1ea47513.akpm@linux-foundation.org> <20090407070835.GM5178@kernel.dk> <20090407002313.fcdd1da0.akpm@linux-foundation.org> <20090407075732.GO5178@kernel.dk> <20090407190913.GA31723@mit.edu> <20090407193239.GE5178@kernel.dk> <20090407214421.GA7031@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Jens Axboe , Andrew Morton , Linux Kernel Developers List , Ext4 Developers List Received: from THUNK.ORG ([69.25.196.29]:59750 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760859AbZDGWTn (ORCPT ); Tue, 7 Apr 2009 18:19:43 -0400 Content-Disposition: inline In-Reply-To: <20090407214421.GA7031@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: Now that we have a distinction between WRITE_SYNC and WRITE_SYNC_PLUG, use WRITE_SYNC_PLUG in __block_write_full_page() to avoid unplugging the block device I/O queue between each page that gets flushed out. The upstream callers of block_write_full_page() which wait for the writes to finish call wait_on_buffer(), wait_on_writeback_range() (which ultimately calls sync_page(), which calls blk_run_backing_dev(), which will unplug the device queue), and so on. Signed-off-by: "Theodore Ts'o" --- We should get this applied to avoid any performance regressions resulting from commit a64c8610. fs/buffer.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 977e12a..95b5390 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1646,7 +1646,8 @@ static int __block_write_full_page(struct inode *inode, struct page *page, struct buffer_head *bh, *head; const unsigned blocksize = 1 << inode->i_blkbits; int nr_underway = 0; - int write_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); + int write_op = (wbc->sync_mode == WB_SYNC_ALL ? + WRITE_SYNC_PLUG : WRITE); BUG_ON(!PageLocked(page)); -- 1.5.6.3