Hi all, Since the last discussion[1], here is a third version of filesystem io type accouting. This version only is implemented in ext4 because I don't add any generic mechanism in buffer layer. Now, in ext4, we can know the number of different IO requests that are issued to the disk from io_stats file. Changes since v2: * Define wrapper function for io type accouting in ext4: submit_bh(), bh_submit_read(), sb_bread(), sb_breadahead() and ll_rw_blocK() are replaced by these wrapper functions. In these wrapper functions, percpu_couters are added to account the number of different IO requests which are issued to the disk. * Add per-device counter: The percpu_counter is moved into ext4_sb_info structure in order to supprt per-device accouting. * Add io_stats_reset to reset counter: io_stats_reset file is created in /sys/fs/ext4/$DEVICE/. We can use 'echo 1 > /sys/fs/ext4/$DEVICE/io_stats_reset' command to reset counter. * Add version information into io_stats: 'Version' field is printed in io_stats in order to userspace tool can parse the format according to the current version. Changes since v1: * Totoally redisgn the implementation: A 'Issue' flag is added in buffer_head structure to let filesystem can check it and do related things. Steven, I don't add the flag into the buffer layer as you said before. I think that it is too tricky if we just OR the __REQ_* flags together. I wish Jens can give some suggestions. Any comments or suggestions are welcome. [1]. http://www.spinics.net/lists/linux-ext4/msg28817.html Regards, Zheng -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
