From 31f7987406497dc65408dee4e84e3f3cc3ffe9cd Mon Sep 17 00:00:00 2001 From: Alexey Klimov Date: Fri, 4 Sep 2015 02:49:58 +0300 Subject: clocksource/drivers/exynos_mct: Use container_of() instead of this_cpu_ptr() 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 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 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 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 Signed-off-by: Daniel Lezcano Reviewed-by: Krzysztof Kozlowski --- drivers/clocksource/exynos_mct.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'drivers/clocksource') diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c index 029f96ab131a..ff44082a0827 100644 --- a/drivers/clocksource/exynos_mct.c +++ b/drivers/clocksource/exynos_mct.c @@ -382,24 +382,28 @@ static void exynos4_mct_tick_start(unsigned long cycles, static int exynos4_tick_set_next_event(unsigned long cycles, struct clock_event_device *evt) { - struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick); + struct mct_clock_event_device *mevt; + mevt = container_of(evt, struct mct_clock_event_device, evt); exynos4_mct_tick_start(cycles, mevt); - return 0; } static int set_state_shutdown(struct clock_event_device *evt) { - exynos4_mct_tick_stop(this_cpu_ptr(&percpu_mct_tick)); + struct mct_clock_event_device *mevt; + + mevt = container_of(evt, struct mct_clock_event_device, evt); + exynos4_mct_tick_stop(mevt); return 0; } static int set_state_periodic(struct clock_event_device *evt) { - struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick); + struct mct_clock_event_device *mevt; unsigned long cycles_per_jiffy; + mevt = container_of(evt, struct mct_clock_event_device, evt); cycles_per_jiffy = (((unsigned long long)NSEC_PER_SEC / HZ * evt->mult) >> evt->shift); exynos4_mct_tick_stop(mevt); -- cgit v1.2.3