0 + 8 * 128 + 120 * 64 = 8824 When SPARSE_IRQ is not set, there is no increase with kernel data size. when NR_CPUS=128, and SPARSE_IRQ is set: text data bss dec hex filename 21837444 4216564 12480736 38534744 24bfe58 vmlinux.before 21837442 4216580 12480736 38534758 24bfe66 vmlinux.after when NR_CPUS=4096, and SPARSE_IRQ is set text data bss dec hex filename 21878619 5610244 13415392 40904255 270263f vmlinux.before 21878617 5610244 13415392 40904253 270263d vmlinux.after Signed-off-by: Yinghai Lu Cc: Linus Torvalds Cc: Andrew Morton LKML-Reference: <4B398ECD.1080506@kernel.org> Signed-off-by: Ingo Molnar IDą