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![]() After this patch 'page-types' can walk over a file's mappings and analyze populated page cache pages mostly without disturbing its state. It maps chunk of file, marks VMA as MADV_RANDOM to turn off readahead, pokes VMA via mincore() to determine cached pages, triggers page-fault only for them, and finally gathers information via pagemap/kpageflags. Before unmap it marks VMA as MADV_SEQUENTIAL for ignoring reference bits. usage: page-types -f <path> If <path> is directory it will analyse all files in all subdirectories. Symlinks are not followed as well as mount points. Hardlinks aren't handled, they'll be dumped as many times as they are found. Recursive walk brings all dentries into dcache and populates page cache of block-devices aka 'Buffers'. Probably it's worth to add ioctl for dumping file page cache as array of PFNs as a replacement for this hackish juggling with mmap/madvise/mincore/pagemap. Also recursive walk could be replaced with dumping cached inodes via some ioctl or debugfs interface followed by openning them via open_by_handle_at, this would fix hardlinks handling and unneeded population of dcache and buffers. This interface might be used as data source for constructing readahead plans and for background optimizations of actively used files. collateral changes: + fix 64-bit LFS: define _FILE_OFFSET_BITS instead of _LARGEFILE64_SOURCE + replace lseek + read with single pread + make show_page_range() reusable after flush usage example: ~/src/linux/tools/vm$ sudo ./page-types -L -f page-types foffset offset flags page-types Inode: 2229277 Size: 89065 (22 pages) Modify: Tue Feb 25 12:00:59 2014 (162 seconds ago) Access: Tue Feb 25 12:01:00 2014 (161 seconds ago) 0 3cbf3b __RU_lA____M________________________ 1 38946a __RU_lA____M________________________ 2 1a3cec __RU_lA____M________________________ 3 1a8321 __RU_lA____M________________________ 4 3af7cc __RU_lA____M________________________ 5 1ed532 __RU_lA_____________________________ 6 2e436a __RU_lA_____________________________ 7 29a35e ___U_lA_____________________________ 8 2de86e ___U_lA_____________________________ 9 3bdfb4 ___U_lA_____________________________ 10 3cd8a3 ___U_lA_____________________________ 11 2afa50 ___U_lA_____________________________ 12 2534c2 ___U_lA_____________________________ 13 1b7a40 ___U_lA_____________________________ 14 17b0be ___U_lA_____________________________ 15 392b0c ___U_lA_____________________________ 16 3ba46a __RU_lA_____________________________ 17 397dc8 ___U_lA_____________________________ 18 1f2a36 ___U_lA_____________________________ 19 21fd30 __RU_lA_____________________________ 20 2c35ba __RU_l______________________________ 21 20f181 __RU_l______________________________ flags page-count MB symbolic-flags long-symbolic-flags 0x000000000000002c 2 0 __RU_l______________________________ referenced,uptodate,lru 0x0000000000000068 11 0 ___U_lA_____________________________ uptodate,lru,active 0x000000000000006c 4 0 __RU_lA_____________________________ referenced,uptodate,lru,active 0x000000000000086c 5 0 __RU_lA____M________________________ referenced,uptodate,lru,active,mmap total 22 0 ~/src/linux/tools/vm$ sudo ./page-types -f / flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000028 21761 85 ___U_l______________________________ uptodate,lru 0x000000000000002c 127279 497 __RU_l______________________________ referenced,uptodate,lru 0x0000000000000068 74160 289 ___U_lA_____________________________ uptodate,lru,active 0x000000000000006c 84469 329 __RU_lA_____________________________ referenced,uptodate,lru,active 0x000000000000007c 1 0 __RUDlA_____________________________ referenced,uptodate,dirty,lru,active 0x0000000000000228 370 1 ___U_l___I__________________________ uptodate,lru,reclaim 0x0000000000000828 49 0 ___U_l_____M________________________ uptodate,lru,mmap 0x000000000000082c 126 0 __RU_l_____M________________________ referenced,uptodate,lru,mmap 0x0000000000000868 137 0 ___U_lA____M________________________ uptodate,lru,active,mmap 0x000000000000086c 12890 50 __RU_lA____M________________________ referenced,uptodate,lru,active,mmap total 321242 1254 Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Borislav Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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