Currently there's three possible values we pass into the flusher thread for the nr_pages arguments: - in sync_inodes_sb and bdi_start_background_writeback: LONG_MAX - in writeback_inodes_sb and wb_check_old_data_flush: global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS) + (inodes_stat.nr_inodes - inodes_stat.nr_unused) - in wakeup_flusher_threads and laptop_mode_timer_fn: global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS) The LONG_MAX cases are triviall explained, as we ignore the nr_to_write value for data integrity writepage in the lowlevel writeback code, and the for_background in bdi_start_background_writeback has it's own check for the background threshold. So far so good, and now it gets interesting. Why does writeback_inodes_sb add the number of used inodes into a value that is in units of pages? And why don't the other callers do this? But seriously, how is the _global_ number of dirty and unstable pages a good indicator for the amount of writeback per-bdi or superblock anyway? Somehow I'd feel much better about doing this calculation all the way down in wb_writeback instead of the callers so we'll at least have one documented place for these insanities. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>