DAMON core layer has its own address space that uses 'unsigned long' for handling addresses. The underlying DAMON operations set implementation translates the core layer address to the real address space that it is working for. For example, vaddr and fvaddr translates the core layer addresses to virtual addresses. However, all operations set layer simply assumes the core layer address will be same to those for the given address space. Since the core layer address uses 'unsigned long', it is ok for virtual addresses. In case of physical address space, however, there can be some cases where 'unsigned long' cannot handle whole address. For example, 32bit arm machines with large physical address extension (LPAE) is such a case[1]. Arm with LPAE is the only reported use case, but similar cases could happen in future. Add a new core layer parameter called 'addr_unit'. Operations set layer can translate a core layer address to the real address by multiplying the parameter value to the core layer address. Support of the parameter is up to each operations layer implementation, though. For example, operations set implementations for virtual address space can simply ignore the parameter. Add the support on paddr, which is the DAMON operations set implementation for the physical address space, as we have a clear use case for that. Patches Sequence ================ The first patch implements the new parameter on DAMON kernel API. Following five patches (patch 2-6) incrementally add support of the new parameter on paddr operations set, for monitoring operations and DAMOS operations for each DAMOS actions. The seventh patch implements DAMON sysfs ABI for letting users control the parameter. Final three patches (patches 8-10) documents the new ABI on design, usage, and ABI documents, respectively. [1] https://lore.kernel.org/20250408075553.959388-1-zuoze1@xxxxxxxxxx SeongJae Park (10): mm/damon/core: add damon_ctx->addr_unit mm/damon/paddr: support addr_unit for access monitoring mm/damon/paddr: support addr_unit for DAMOS_PAGEOUT mm/damon/paddr: support addr_unit for DAMOS_LRU_[DE]PRIO mm/damon/paddr: support addr_unit for MIGRATE_{HOT,COLD} mm/damon/paddr: support addr_unit for DAMOS_STAT mm/damon/sysfs: implement addr_unit file under context dir Docs/mm/damon/design: document 'address unit' parameter Docs/admin-guide/mm/damon/usage: document addr_unit file Docs/ABI/damon: document addr_unit file .../ABI/testing/sysfs-kernel-mm-damon | 7 ++ Documentation/admin-guide/mm/damon/usage.rst | 11 ++- Documentation/mm/damon/design.rst | 16 +++- include/linux/damon.h | 2 + mm/damon/core.c | 3 + mm/damon/paddr.c | 95 ++++++++++++------- mm/damon/sysfs.c | 26 +++++ 7 files changed, 119 insertions(+), 41 deletions(-) base-commit: b32e0b4ccfbe176a541e7feee0cdaebb957738e7 -- 2.39.5
