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Diffstat (limited to 'Documentation/filesystems/proc.txt')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 73 |
1 files changed, 36 insertions, 37 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index f566ad9bcb7..d831d24d2a6 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -923,45 +923,44 @@ CPUs. The "procs_blocked" line gives the number of processes currently blocked, waiting for I/O to complete. + 1.9 Ext4 file system parameters ------------------------------ -Ext4 file system have one directory per partition under /proc/fs/ext4/ -# ls /proc/fs/ext4/hdc/ -group_prealloc max_to_scan mb_groups mb_history min_to_scan order2_req -stats stream_req - -mb_groups: -This file gives the details of multiblock allocator buddy cache of free blocks - -mb_history: -Multiblock allocation history. - -stats: -This file indicate whether the multiblock allocator should start collecting -statistics. The statistics are shown during unmount - -group_prealloc: -The multiblock allocator normalize the block allocation request to -group_prealloc filesystem blocks if we don't have strip value set. -The stripe value can be specified at mount time or during mke2fs. - -max_to_scan: -How long multiblock allocator can look for a best extent (in found extents) - -min_to_scan: -How long multiblock allocator must look for a best extent - -order2_req: -Multiblock allocator use 2^N search using buddies only for requests greater -than or equal to order2_req. The request size is specfied in file system -blocks. A value of 2 indicate only if the requests are greater than or equal -to 4 blocks. - -stream_req: -Files smaller than stream_req are served by the stream allocator, whose -purpose is to pack requests as close each to other as possible to -produce smooth I/O traffic. Avalue of 16 indicate that file smaller than 16 -filesystem block size will use group based preallocation. + +Information about mounted ext4 file systems can be found in +/proc/fs/ext4. Each mounted filesystem will have a directory in +/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or +/proc/fs/ext4/dm-0). The files in each per-device directory are shown +in Table 1-10, below. + +Table 1-10: Files in /proc/fs/ext4/<devname> +.............................................................................. + File Content + mb_groups details of multiblock allocator buddy cache of free blocks + mb_history multiblock allocation history + stats controls whether the multiblock allocator should start + collecting statistics, which are shown during the unmount + group_prealloc 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 + max_to_scan The maximum number of extents the multiblock allocator + will search to find the best extent + min_to_scan The minimum number of extents the multiblock allocator + will search to find the best extent + order2_req Tuning parameter which controls the minimum size for + requests (as a power of 2) where the buddy cache is + used + stream_req 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. +inode_readahead 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 +.............................................................................. + ------------------------------------------------------------------------------ Summary |