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author | Alexey Klimov <alexey.klimov@linaro.org> | 2015-09-04 02:49:58 +0300 |
---|---|---|
committer | Daniel Lezcano <daniel.lezcano@linaro.org> | 2015-10-15 17:42:03 +0200 |
commit | 31f7987406497dc65408dee4e84e3f3cc3ffe9cd (patch) | |
tree | 6b72e2d6b32218b93a7b1e95c145ad2c4ff8cc0c | |
parent | ba49af35be8a41af7f00a37902a2d70764078bc5 (diff) | |
download | linux-31f7987406497dc65408dee4e84e3f3cc3ffe9cd.tar.bz2 |
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 <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 <alexey.klimov@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
-rw-r--r-- | drivers/clocksource/exynos_mct.c | 12 |
1 files changed, 8 insertions, 4 deletions
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); |