Andrew, This enlarges the default readahead size from 128K to 512K. To avoid possible regressions, also do - scale down readahead size on small device and small memory - thrashing safe context readahead - add readahead tracing/stats support to help expose possible problems Besides, the patchset also includes several algorithm updates: - no start-of-file readahead after lseek - faster radix_tree_next_hole()/radix_tree_prev_hole() - pagecache context based mmap read-around Changes since v2: - add notes on readahead size - limit read-around size for small memory system, but don't limit readahead size - bug fix: allow context readahead async size grow to its full size - bug fix: let radix_tree_lookup_leaf_node() handle the height=1 case Changes since v1: - update mmap read-around heuristics (Thanks to Nick Piggin) - radix_tree_lookup_leaf_node() for the pagecache based mmap read-around - use __print_symbolic() to show readahead pattern names (Thanks to Steven Rostedt) - scale down readahead size proportional to system memory (Thanks to Matt Mackall) - add readahead size kernel parameter (by Nikanth Karthikesan) - add comments from Christian Ehrhardt Changes since RFC: - move the lenthy intro text to individual patch changelogs - treat get_capacity()==0 as uninitilized value (Thanks to Vivek Goyal) - increase readahead size limit for small devices (Thanks to Jens Axboe) - add fio test results by Vivek Goyal [PATCH 01/16] readahead: limit readahead size for small devices [PATCH 02/16] readahead: retain inactive lru pages to be accessed soon [PATCH 03/16] readahead: bump up the default readahead size [PATCH 04/16] readahead: make default readahead size a kernel parameter [PATCH 05/16] readahead: limit read-ahead size for small memory systems [PATCH 06/16] readahead: add notes on readahead size [PATCH 07/16] readahead: replace ra->mmap_miss with ra->ra_flags [PATCH 08/16] readahead: thrashing safe context readahead [PATCH 09/16] readahead: record readahead patterns [PATCH 10/16] readahead: add tracing event [PATCH 11/16] readahead: add /debug/readahead/stats [PATCH 12/16] readahead: dont do start-of-file readahead after lseek() [PATCH 13/16] radixtree: introduce radix_tree_lookup_leaf_node() [PATCH 14/16] radixtree: speed up the search for hole [PATCH 15/16] readahead: reduce MMAP_LOTSAMISS for mmap read-around [PATCH 16/16] readahead: pagecache context based mmap read-around Documentation/kernel-parameters.txt | 4 block/blk-core.c | 3 block/genhd.c | 24 + fs/fuse/inode.c | 2 fs/read_write.c | 3 include/linux/fs.h | 64 +++ include/linux/mm.h | 8 include/linux/radix-tree.h | 2 include/trace/events/readahead.h | 78 ++++ lib/radix-tree.c | 104 ++++- mm/Kconfig | 13 mm/filemap.c | 34 + mm/readahead.c | 458 ++++++++++++++++++++++---- 13 files changed, 688 insertions(+), 109 deletions(-) Thanks, Fengguang -- 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>