On PowerPC Book3S64, MMU is selected at runtime, so macros like PMD_SHIFT are effectively runtime variables in the Book3S64 code. THP swap code uses these macros for e.g. to size some of its array data structures based on PMD_ORDER. This patch series makes that usage dependent on the runtime variable.
Sayali did some performance runs of this on Book3S64 with Radix and it gives 40-50% performance improvement. We also plan to run it with Hash, will soon update the results. Note that this patch series is based out of linux-next (next-20260608). Ritesh Harjani (IBM) (4): include/linux/swap.h: Remove unused leftovers mm, swap: make SWAPFILE_CLUSTER runtime mm, swap: make SWAP_NR_ORDERS runtime powerpc: Kconfig: Enable THP_SWAP on Book3S64 arch/powerpc/platforms/Kconfig.cputype | 1 + include/linux/swap.h | 17 +--- mm/swap.h | 5 +- mm/swap_table.h | 6 +- mm/swapfile.c | 132 ++++++++++++++++++------- 5 files changed, 106 insertions(+), 55 deletions(-) -- 2.39.5
