Hi, Version 2 re-structured to better follow the structure of Chirstoph's original patchset (linked below). Functions renamed and other suggestions on v1 from Roman implemented. This version also adds an attempt at implementing object migration for the dcache, appropriate filesystem folk CC'd. Please see comments below in 'dcache' section. Applies on top of Linus' tree (tag: v5.1-rc3). This is a patch set implementing movable objects within the SLUB allocator. This is work based on Christopher's patch set: https://lore.kernel.org/patchwork/project/lkml/list/?series=377335 The original code logic is from that set and implemented by Christopher. Clean up, refactoring, documentation, and additional features by myself. Blame for any bugs remaining falls solely with myself. Patches using Christopher's code use the Co-developed-by tag but do not currently have his SOB tag. The core of the implementation is now contained within the first 4 patches (primarily patch #4). Patches 7,8,10 add test code including a test modules to play around with this. With the series applied one can see functionality in action by using the slabinfo command on the xarray slab cache slabinfo radix_tree_node -r The NUMA stuff works as claimed with the radix_tree_node slab cache. dcache ------ The dcache patches are my best effort on top of Christoph's original work. The dcache has changed a lot since then (2009). FTR one month ago was the first time I have ever opened fs/dcache.c. I have been playing with this for at least two weeks without any functional changes to the dcache patches - I do not think me playing with it more is going to improve my understanding of the dcache so I am asking for help here. I've been testing in Qemu (both using ramdisk filesystem and a disk image filesystem) as well as on bare metal. Shrinking the dcache with: slabinfo dentry -s produces _more_ partial slabs than before and repeated calls continue to increase the number of partial slabs. Although the initial calls do decrease the total number of cached objects. I cannot explain this. During development I added a bunch of printks and the majority of dentry slab objects are skipped during the isolation function due to the following check from d_isolate(): if (dentry->d_inode && !mapping_cap_writeback_dirty(dentry->d_inode->i_mapping)) ... /* skip object*/ I cannot explain the large number of dentry objects skipped by this clause. Any suggestions no matter how wild very much appreciated. Tips on files I should study or anything else I could do to better understand what is needed to understand to work with this. So far I have been primarily trying to grok the VFS and the dcache in particular via: fs/dcache.c include/linux/fs.h include/linux/dcache.h Documentation/filesystems/vfs.txt I also tried using the cache shrinkers echo 2 > /proc/sys/vm/drop_caches Then shrinking the dentry slab cache. This resulted in a bunch of things disappearing e.g. sysfs gets unmounted, /home directory contents disappear. Again, I cannot explain this. Should this be doable if this series was implemented correctly? Thanks for taking the time to look at this. Tobin. Tobin C. Harding (14): slub: Add isolate() and migrate() methods tools/vm/slabinfo: Add support for -C and -M options slub: Sort slab cache list slub: Slab defrag core tools/vm/slabinfo: Add remote node defrag ratio output tools/vm/slabinfo: Add defrag_used_ratio output tools/testing/slab: Add object migration test module tools/testing/slab: Add object migration test suite xarray: Implement migration function for objects tools/testing/slab: Add XArray movable objects tests slub: Enable moving objects to/from specific nodes slub: Enable balancing slabs across nodes dcache: Provide a dentry constructor dcache: Implement object migration Documentation/ABI/testing/sysfs-kernel-slab | 14 + fs/dcache.c | 124 ++- include/linux/slab.h | 71 ++ include/linux/slub_def.h | 10 + lib/radix-tree.c | 13 + lib/xarray.c | 46 ++ mm/Kconfig | 7 + mm/slab_common.c | 2 +- mm/slub.c | 819 ++++++++++++++++++-- tools/testing/slab/Makefile | 10 + tools/testing/slab/slub_defrag.c | 567 ++++++++++++++ tools/testing/slab/slub_defrag.py | 451 +++++++++++ tools/testing/slab/slub_defrag_xarray.c | 211 +++++ tools/vm/slabinfo.c | 51 +- 14 files changed, 2303 insertions(+), 93 deletions(-) create mode 100644 tools/testing/slab/Makefile create mode 100644 tools/testing/slab/slub_defrag.c create mode 100755 tools/testing/slab/slub_defrag.py create mode 100644 tools/testing/slab/slub_defrag_xarray.c -- 2.21.0
