Hi, Here 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. After movable objects are implemented a number of useful features become possible. Some of these are implemented in this series, including: - Cache defragmentation. Currently the SLUB allocator is susceptible to internal fragmentation. This occurs when a large number of cached objects are allocated and then freed in an arbitrary order. As the cache fragments the number of pages used by the partial slabs list increases. This wastes memory. Patch set implements the machinery to facilitate conditional cache defragmentation (via kmem_cache_defrag()) and unconditional defragmentation (via kmem_cache_shrink()). Various sysfs knobs are provided to interact with and configure this. Patch set implements movable objects and cache defragmentation for the XArray. - Moving objects to and from a specific NUMA node. - Balancing objects across all NUMA nodes. We add a test module to facilitate playing around with movable objects and a python test suite that uses the module. Everything except the NUMA stuff was tested on bare metal, the NUMA stuff was tested with Qemu NUMA emulation. Possible further work: 1. Implementing movable objects for the inode and dentry caches. 2. Tying into the page migration and page defragmentation logic so that so far unmovable pages that are in the way of creating a contiguous block of memory will become movable. This would mean checking for slab pages in the migration logic and calling slab to see if it can move the page by migrating all objects. Patch 1-4 - Implement Slab Movable Objects. Patch 5-9 - Implement slab cache defragmentation. Patch 10 - Adds the test module. Patch 11 - Adds the test suite. Patch 12-13 - Adds object migration to the XArray (and test code). Patch 14 - Adds moving objects to and from a specified NUMA node. Patch 15 - Adds object balancing across all NUMA nodes. Patch 12 introduces an build warning, I tried a bunch of things and I couldn't work out what it should be. linux/lib/xarray.c:1961:16: warning: comparison between pointer and zero character constant [-Wpointer-compare] if (!xa || xa == XA_FREE_MARK) ^~ linux/lib/xarray.c:1961:13: note: did you mean to dereference the pointer? if (!xa || xa == XA_FREE_MARK) Perhaps you will put me out of my misery Willy and just tell me what its supposed to be. Patch 14 and 15 are particularly early stage (I hacked those :) thanks, Tobin. Tobin C. Harding (15): slub: Create sysfs field /sys/slab/<cache>/ops slub: Add isolate() and migrate() methods tools/vm/slabinfo: Add support for -C and -F options slub: Enable Slab Movable Objects (SMO) slub: Sort slab cache list tools/vm/slabinfo: Add remote node defrag ratio output slub: Add defrag_used_ratio field and sysfs support tools/vm/slabinfo: Add defrag_used_ratio output slub: Enable slab defragmentation using SMO 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 move _all_ objects to node slub: Enable balancing slab objects across nodes Documentation/ABI/testing/sysfs-kernel-slab | 14 + include/linux/slab.h | 70 ++ include/linux/slub_def.h | 10 + lib/radix-tree.c | 13 + lib/xarray.c | 44 ++ mm/Kconfig | 7 + mm/slab_common.c | 6 +- mm/slub.c | 800 ++++++++++++++++++-- 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 +- 13 files changed, 2172 insertions(+), 82 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
