Using pahole, we can see that there are some padding holes in the current pcpu_chunk structure,Adjusting the layout of pcpu_chunk can reduce these holes,decreasing its size from 192 bytes to 128 bytes and eliminating a wasted cache line. With allmodconfig (CONFIG_PERCPU_STATS + NEED_PCPUOBJ_EXT) Before: /* size: 256, cachelines: 4, members: 19 */ After: /* size: 192, cachelines: 3, members: 19 */ with NEED_PCPUOBJ_EXT Before: struct pcpu_chunk { struct list_head list; /* 0 16 */ int free_bytes; /* 16 4 */ struct pcpu_block_md chunk_md; /* 20 32 */ /* XXX 4 bytes hole, try to pack */ long unsigned int * bound_map; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ void * base_addr __attribute__((__aligned__(64))); /* 64 8 */ long unsigned int * alloc_map; /* 72 8 */ struct pcpu_block_md * md_blocks; /* 80 8 */ void * data; /* 88 8 */ bool immutable; /* 96 1 */ bool isolated; /* 97 1 */ /* XXX 2 bytes hole, try to pack */ int start_offset; /* 100 4 */ int end_offset; /* 104 4 */ /* XXX 4 bytes hole, try to pack */ struct obj_cgroup * * obj_cgroups; /* 112 8 */ int nr_pages; /* 120 4 */ int nr_populated; /* 124 4 */ /* --- cacheline 2 boundary (128 bytes) --- */ int nr_empty_pop_pages; /* 128 4 */ /* XXX 4 bytes hole, try to pack */ long unsigned int populated[]; /* 136 0 */ /* size: 192, cachelines: 3, members: 17 */ /* sum members: 122, holes: 4, sum holes: 14 */ /* padding: 56 */ /* forced alignments: 1 */ } __attribute__((__aligned__(64))); After: struct pcpu_chunk { struct list_head list; /* 0 16 */ int free_bytes; /* 16 4 */ struct pcpu_block_md chunk_md; /* 20 32 */ /* XXX 4 bytes hole, try to pack */ long unsigned int * bound_map; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ void * base_addr __attribute__((__aligned__(64))); /* 64 8 */ long unsigned int * alloc_map; /* 72 8 */ struct pcpu_block_md * md_blocks; /* 80 8 */ void * data; /* 88 8 */ bool immutable; /* 96 1 */ bool isolated; /* 97 1 */ /* XXX 2 bytes hole, try to pack */ int start_offset; /* 100 4 */ int end_offset; /* 104 4 */ int nr_pages; /* 108 4 */ int nr_populated; /* 112 4 */ int nr_empty_pop_pages; /* 116 4 */ struct obj_cgroup * * obj_cgroups; /* 120 8 */ /* --- cacheline 2 boundary (128 bytes) --- */ long unsigned int populated[]; /* 128 0 */ /* size: 128, cachelines: 2, members: 17 */ /* sum members: 122, holes: 2, sum holes: 6 */ /* forced alignments: 1 */ } __attribute__((__aligned__(64))); Link: https://lore.kernel.org/20260511070309.44044-1-zenghongling@kylinos.cn Signed-off-by: zenghongling <zenghongling@kylinos.cn> Suggested-by: Dennis Zhou <dennis@kernel.org> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>