* [PATCH v3 1/2] clocksource/drivers/dw_apb_timer: Inline apbt_readl and apbt_writel
2015-11-25 15:48 [PATCH v3 0/2] clocksource/drivers/dw_apb_timer: improve performance a bit Jisheng Zhang
@ 2015-11-25 15:48 ` Jisheng Zhang
2015-11-25 15:48 ` [PATCH v3 2/2] clocksource/drivers/dw_apb_timer: Use {readl|writel}_relaxed in critical path Jisheng Zhang
2015-11-25 15:50 ` [PATCH v3 0/2] clocksource/drivers/dw_apb_timer: improve performance a bit Jisheng Zhang
2 siblings, 0 replies; 4+ messages in thread
From: Jisheng Zhang @ 2015-11-25 15:48 UTC (permalink / raw)
To: linux-arm-kernel
It seems gcc can automatically inline apbt_writel() for us, but
apbt_real isn't inlined. This patch makes them inline to get a trivial
performance improvement: the time __apbt_read_clocksource() spends on
Marvell BG4CT platform:
before the patch 1275240ns on average
after the patch 1263240ns on average
so we get 1% performance improvement.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
drivers/clocksource/dw_apb_timer.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c
index 3a6d9db..114696b 100644
--- a/drivers/clocksource/dw_apb_timer.c
+++ b/drivers/clocksource/dw_apb_timer.c
@@ -49,13 +49,13 @@ clocksource_to_dw_apb_clocksource(struct clocksource *cs)
return container_of(cs, struct dw_apb_clocksource, cs);
}
-static u32 apbt_readl(struct dw_apb_timer *timer, unsigned long offs)
+static inline u32 apbt_readl(struct dw_apb_timer *timer, unsigned long offs)
{
return readl(timer->base + offs);
}
-static void apbt_writel(struct dw_apb_timer *timer, u32 val,
- unsigned long offs)
+static inline void apbt_writel(struct dw_apb_timer *timer, u32 val,
+ unsigned long offs)
{
writel(val, timer->base + offs);
}
--
2.6.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v3 2/2] clocksource/drivers/dw_apb_timer: Use {readl|writel}_relaxed in critical path
2015-11-25 15:48 [PATCH v3 0/2] clocksource/drivers/dw_apb_timer: improve performance a bit Jisheng Zhang
2015-11-25 15:48 ` [PATCH v3 1/2] clocksource/drivers/dw_apb_timer: Inline apbt_readl and apbt_writel Jisheng Zhang
@ 2015-11-25 15:48 ` Jisheng Zhang
2015-11-25 15:50 ` [PATCH v3 0/2] clocksource/drivers/dw_apb_timer: improve performance a bit Jisheng Zhang
2 siblings, 0 replies; 4+ messages in thread
From: Jisheng Zhang @ 2015-11-25 15:48 UTC (permalink / raw)
To: linux-arm-kernel
It's safe to use the relaxed version. From another side, the relaxed io
accessor macros are available on all architectures now, so we can use
the relaxed versions to get a trivial system performance improvement,
we measured time the following functions spent on Marvell BG4CT:
__apbt_read_clocksource():
before the patch: 1263240ns on average
after the patch: 1250080ns on average
improved by 1%
apbt_eoi():
before the patch: 1290960ns on average
after the patch: 1248240ns on average
apbt_next_event():
before the patch: 3333660ns on average
after the patch: 1322040ns on average
improved by 60%!
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
drivers/clocksource/dw_apb_timer.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c
index 114696b..6334526 100644
--- a/drivers/clocksource/dw_apb_timer.c
+++ b/drivers/clocksource/dw_apb_timer.c
@@ -60,6 +60,17 @@ static inline void apbt_writel(struct dw_apb_timer *timer, u32 val,
writel(val, timer->base + offs);
}
+static inline u32 apbt_readl_relaxed(struct dw_apb_timer *timer, unsigned long offs)
+{
+ return readl_relaxed(timer->base + offs);
+}
+
+static inline void apbt_writel_relaxed(struct dw_apb_timer *timer, u32 val,
+ unsigned long offs)
+{
+ writel_relaxed(val, timer->base + offs);
+}
+
static void apbt_disable_int(struct dw_apb_timer *timer)
{
u32 ctrl = apbt_readl(timer, APBTMR_N_CONTROL);
@@ -81,7 +92,7 @@ void dw_apb_clockevent_pause(struct dw_apb_clock_event_device *dw_ced)
static void apbt_eoi(struct dw_apb_timer *timer)
{
- apbt_readl(timer, APBTMR_N_EOI);
+ apbt_readl_relaxed(timer, APBTMR_N_EOI);
}
static irqreturn_t dw_apb_clockevent_irq(int irq, void *data)
@@ -200,13 +211,13 @@ static int apbt_next_event(unsigned long delta,
struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt);
/* Disable timer */
- ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL);
+ ctrl = apbt_readl_relaxed(&dw_ced->timer, APBTMR_N_CONTROL);
ctrl &= ~APBTMR_CONTROL_ENABLE;
- apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+ apbt_writel_relaxed(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
/* write new count */
- apbt_writel(&dw_ced->timer, delta, APBTMR_N_LOAD_COUNT);
+ apbt_writel_relaxed(&dw_ced->timer, delta, APBTMR_N_LOAD_COUNT);
ctrl |= APBTMR_CONTROL_ENABLE;
- apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
+ apbt_writel_relaxed(&dw_ced->timer, ctrl, APBTMR_N_CONTROL);
return 0;
}
@@ -342,7 +353,8 @@ static cycle_t __apbt_read_clocksource(struct clocksource *cs)
struct dw_apb_clocksource *dw_cs =
clocksource_to_dw_apb_clocksource(cs);
- current_count = apbt_readl(&dw_cs->timer, APBTMR_N_CURRENT_VALUE);
+ current_count = apbt_readl_relaxed(&dw_cs->timer,
+ APBTMR_N_CURRENT_VALUE);
return (cycle_t)~current_count;
}
--
2.6.2
^ permalink raw reply related [flat|nested] 4+ messages in thread