What: /sys/fs/ext4//mb_stats Date: March 2008 Contact: "Theodore Ts'o" Description: Controls whether the multiblock allocator should collect statistics, which are shown during the unmount. 1 means to collect statistics, 0 means not to collect statistics What: /sys/fs/ext4//mb_group_prealloc Date: March 2008 Contact: "Theodore Ts'o" Description: The multiblock allocator will round up allocation requests to a multiple of this tuning parameter if the stripe size is not set in the ext4 superblock What: /sys/fs/ext4//mb_max_to_scan Date: March 2008 Contact: "Theodore Ts'o" Description: The maximum number of extents the multiblock allocator will search to find the best extent What: /sys/fs/ext4//mb_min_to_scan Date: March 2008 Contact: "Theodore Ts'o" Description: The minimum number of extents the multiblock allocator will search to find the best extent What: /sys/fs/ext4//mb_order2_req Date: March 2008 Contact: "Theodore Ts'o" Description: Tuning parameter which controls the minimum size for requests (as a power of 2) where the buddy cache is used What: /sys/fs/ext4//mb_stream_req Date: March 2008 Contact: "Theodore Ts'o" Description: Files which have fewer blocks than this tunable parameter will have their blocks allocated out of a block group specific preallocation pool, so that small files are packed closely together. Each large file will have its blocks allocated out of its own unique preallocation pool. What: /sys/fs/ext4//inode_readahead_blks Date: March 2008 Contact: "Theodore Ts'o" Description: Tuning parameter which controls the maximum number of inode table blocks that ext4's inode table readahead algorithm will pre-read into the buffer cache What: /sys/fs/ext4//delayed_allocation_blocks Date: March 2008 Contact: "Theodore Ts'o" Description: This file is read-only and shows the number of blocks that are dirty in the page cache, but which do not have their location in the filesystem allocated yet. What: /sys/fs/ext4//lifetime_write_kbytes Date: March 2008 Contact: "Theodore Ts'o" Description: This file is read-only and shows the number of kilobytes of data that have been written to this filesystem since it was created. What: /sys/fs/ext4//session_write_kbytes Date: March 2008 Contact: "Theodore Ts'o" Description: This file is read-only and shows the number of kilobytes of data that have been written to this filesystem since it was mounted. What: /sys/fs/ext4//inode_goal Date: June 2008 Contact: "Theodore Ts'o" Description: Tuning parameter which (if non-zero) controls the goal inode used by the inode allocator in preference to all other allocation heuristics. This is intended for debugging use only, and should be 0 on production systems. What: /sys/fs/ext4//max_writeback_mb_bump Date: September 2009 Contact: "Theodore Ts'o" Description: The maximum number of megabytes the writeback code will try to write out before move on to another inode. What: /sys/fs/ext4//extent_max_zeroout_kb Date: August 2012 Contact: "Theodore Ts'o" Description: The maximum number of kilobytes which will be zeroed out in preference to creating a new uninitialized extent when manipulating an inode's extent tree. Note that using a larger value will increase the variability of time necessary to complete a random write operation (since a 4k random write might turn into a much larger write due to the zeroout operation). What: /sys/fs/ext4//journal_task Date: February 2019 Contact: "Theodore Ts'o" Description: This file is read-only and shows the pid of journal thread in current pid-namespace or 0 if task is unreachable.