From: Mandeep Singh Baines <m...@chromium.org>
Saves one register read. Note that the upper count only changes every
~178 seconds with a 24MHz source clock, so it's likely it hasn't
changed from call to call.
Before: 1323852 us for 1000000 gettimeofday in userspace
After: 1173084 us for 1000000 gettimeofday in userspace
Note that even with this change the CPU is in exynos_frc_read() more
than 2% of the time in real world profiles of ChromeOS. That
indicates that it's important to optimize.
Signed-off-by: Mandeep Singh Baines <m...@chromium.org>
Signed-off-by: Andrew Bresticker <abres...@chromium.org>
Signed-off-by: Doug Anderson <diand...@chromium.org>
---
drivers/clocksource/exynos_mct.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index ba3a683..7cbe4aa 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -167,8 +167,8 @@ static void exynos4_mct_frc_start(u32 hi, u32 lo)
static inline cycle_t notrace _exynos4_frc_read(void)
{
- unsigned int lo, hi;
- u32 hi2 = __raw_readl(reg_base + EXYNOS4_MCT_G_CNT_U);
+ u32 lo, hi;
+ static u32 hi2;
do {
hi = hi2;
--
2.0.0.526.g5318336
--
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