linux-ext4 - [PATCH 0/2] [RFC] blkdev: flush generation optimization

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Date:	Sun, 14 Apr 2013 23:31:17 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	ext4 development <linux-ext4@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
CC:	Jan Kara <jack@...e.cz>, axboe@...nel.dk
Subject: [PATCH 0/2] [RFC] blkdev: flush generation optimization

Some filesystems try to optimize barrier flushes by maintaining
fs-specific generation counters, but if we introduce generic
flush generation counter for block device filesystems may use
it for fdatasync(2) optimization. Optimization should works if
userspace performs mutli-threaded IO with a lot of fdatasync()
Here are graphs for a test where each task performs random buffered writes
to dedicated file and performs fdatasync(2) after each operation.

Axis: x=nr_tasks, y=write_iops

View attachment "fsync_test.fio" of type "text/plain" (322 bytes)

Download attachment "ssd-fsync.png" of type "image/png" (5313 bytes)

Download attachment "hdd-fsync.png" of type "image/png" (5566 bytes)

TOC:
0001 blkdev: add flush generation counter
0002 ext4: Add fdatasync scalability optimization