On 09/04/2015 01:49 AM, Alexey Klimov wrote:
Since evt structure is embedded in per-CPU mevt structure it's definitely faster to use container_of() to get access to mevt if we have evt (for example as incoming function argument) instead of more expensive approach with this_cpu_ptr(&percpu_mct_tick). this_cpu_ptr() on per-CPU mevt structure leads to access to cp15 to get cpu id and arithmetic operations. Container_of() is cheaper since it's just one asm instruction. This should work if used evt pointer is correct and owned by local mevt structure.For example, before this patch set_state_shutdown() looks like: 4a4: e92d4010 push {r4, lr} 4a8: e3004000 movw r4, #0 4ac: ebfffffe bl 0 <debug_smp_processor_id> 4b0: e3003000 movw r3, #0 4b4: e3404000 movt r4, #0 4b8: e3403000 movt r3, #0 4bc: e7933100 ldr r3, [r3, r0, lsl #2] 4c0: e0844003 add r4, r4, r3 4c4: e59400c0 ldr r0, [r4, #192] ; 0xc0 4c8: ebffffd4 bl 420 <exynos4_mct_tick_stop.isra.1> 4cc: e3a00000 mov r0, #0 4d0: e8bd8010 pop {r4, pc} With this patch: 4a4: e92d4010 push {r4, lr} 4a8: e59000c0 ldr r0, [r0, #192] ; 0xc0 4ac: ebffffdb bl 420 <exynos4_mct_tick_stop.isra.1> 4b0: e3a00000 mov r0, #0 4b4: e8bd8010 pop {r4, pc} Also, for me size of exynos_mct.o decreased from 84588 bytes to 83956. Signed-off-by: Alexey Klimov <[email protected]> ---
Despite the RFC I applied the patch as it seems simple enough and it has been reviewed by Krzysztof.
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