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authorJisheng Zhang <jszhang@marvell.com>2015-07-04 13:06:43 +0800
committerDaniel Lezcano <daniel.lezcano@linaro.org>2015-08-10 11:40:53 +0200
commit8b5f0010fe0d666bb8dfc74b881f2401324a0e89 (patch)
treeccb713dbab20501a9514cb71455fc123395fb88e /drivers/clocksource
parent79e436d3a7d0510dfe6be3973efd78f6ccfe1492 (diff)
downloadlinux-8b5f0010fe0d666bb8dfc74b881f2401324a0e89.tar.bz2
clockevents/drivers/dw_apb_timer: Add dynamic irq flag to the timer
Commit d2348fb6fdc6 ("tick: Dynamically set broadcast irq affinity") adds one excellent feature CLOCK_EVT_FEAT_DYNIRQ to let the core set the interrupt affinity of the broadcast interrupt to the cpu which has the earliest expiry time. This patch adds CLOCK_EVT_FEAT_DYNIRQ flag to avoid unnecessary wakeups and IPIs when the dw_apb_timer is used as broadcast timer. A simple test: ~ # rm /tmp/test.sh ~ # cat > /tmp/test.sh cat /proc/interrupts for i in `seq 10` ; do sleep $i; done cat /proc/interrupts ~ # chmod +x /tmp/test.sh ~ # taskset 0x2 /tmp/test.sh without the patch: CPU0 CPU1 27: 115 36 GIC 27 arch_timer 45: 62 0 GIC 45 mmc0 160: 88 0 interrupt-controller 8 timer 227: 0 0 interrupt-controller 4 f7e81400.i2c 228: 0 0 interrupt-controller 5 f7e81800.i2c 229: 0 0 interrupt-controller 7 dw_spi65535 230: 0 0 interrupt-controller 21 f7e84000.i2c 231: 0 0 interrupt-controller 20 f7e84800.i2c 265: 445 0 interrupt-controller 8 serial IPI0: 0 0 CPU wakeup interrupts IPI1: 0 11 Timer broadcast interrupts IPI2: 56 104 Rescheduling interrupts IPI3: 0 0 Function call interrupts IPI4: 0 4 Single function call interrupts IPI5: 0 0 CPU stop interrupts IPI6: 25 27 IRQ work interrupts IPI7: 0 0 completion interrupts IPI8: 0 0 CPU backtrace Err: 0 CPU0 CPU1 27: 115 38 GIC 27 arch_timer 45: 62 0 GIC 45 mmc0 160: 160 0 interrupt-controller 8 timer 227: 0 0 interrupt-controller 4 f7e81400.i2c 228: 0 0 interrupt-controller 5 f7e81800.i2c 229: 0 0 interrupt-controller 7 dw_spi65535 230: 0 0 interrupt-controller 21 f7e84000.i2c 231: 0 0 interrupt-controller 20 f7e84800.i2c 265: 514 0 interrupt-controller 8 serial IPI0: 0 0 CPU wakeup interrupts IPI1: 0 83 Timer broadcast interrupts IPI2: 56 104 Rescheduling interrupts IPI3: 0 0 Function call interrupts IPI4: 0 4 Single function call interrupts IPI5: 0 0 CPU stop interrupts IPI6: 25 46 IRQ work interrupts IPI7: 0 0 completion interrupts IPI8: 0 0 CPU backtrace Err: 0 cpu0 get 160-88=72 timer interrupts, CPU1 got 83-11=72 broadcast timer IPIs So, overall system got 72+72=144 wake ups and 72 broadcast timer IPIs With the patch: CPU0 CPU1 27: 107 37 GIC 27 arch_timer 45: 62 0 GIC 45 mmc0 160: 66 7 interrupt-controller 8 timer 227: 0 0 interrupt-controller 4 f7e81400.i2c 228: 0 0 interrupt-controller 5 f7e81800.i2c 229: 0 0 interrupt-controller 7 dw_spi65535 230: 0 0 interrupt-controller 21 f7e84000.i2c 231: 0 0 interrupt-controller 20 f7e84800.i2c 265: 311 0 interrupt-controller 8 serial IPI0: 0 0 CPU wakeup interrupts IPI1: 2 4 Timer broadcast interrupts IPI2: 58 100 Rescheduling interrupts IPI3: 0 0 Function call interrupts IPI4: 0 4 Single function call interrupts IPI5: 0 0 CPU stop interrupts IPI6: 21 24 IRQ work interrupts IPI7: 0 0 completion interrupts IPI8: 0 0 CPU backtrace Err: 0 CPU0 CPU1 27: 107 39 GIC 27 arch_timer 45: 62 0 GIC 45 mmc0 160: 69 75 interrupt-controller 8 timer 227: 0 0 interrupt-controller 4 f7e81400.i2c 228: 0 0 interrupt-controller 5 f7e81800.i2c 229: 0 0 interrupt-controller 7 dw_spi65535 230: 0 0 interrupt-controller 21 f7e84000.i2c 231: 0 0 interrupt-controller 20 f7e84800.i2c 265: 380 0 interrupt-controller 8 serial IPI0: 0 0 CPU wakeup interrupts IPI1: 3 6 Timer broadcast interrupts IPI2: 60 100 Rescheduling interrupts IPI3: 0 0 Function call interrupts IPI4: 0 4 Single function call interrupts IPI5: 0 0 CPU stop interrupts IPI6: 21 45 IRQ work interrupts IPI7: 0 0 completion interrupts IPI8: 0 0 CPU backtrace Err: 0 cpu0 got 69-66=3, cpu1 got 75-7=68 timer interrupts. cpu0 got 3-2=1 broadcast timer IPIs, cpu1 got 6-4=2 broadcast timer IPIs. So, overall system got 3+68+1+2=74 wakeups and 1+2=3 broadcast timer IPIs This patch removes 50% wakeups and almost 100% broadcast timer IPIs! Signed-off-by: Jisheng Zhang <jszhang@marvell.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/dw_apb_timer.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c
index 97ba7cbc2cbd..c76c75006ea6 100644
--- a/drivers/clocksource/dw_apb_timer.c
+++ b/drivers/clocksource/dw_apb_timer.c
@@ -248,7 +248,8 @@ dw_apb_clockevent_init(int cpu, const char *name, unsigned rating,
&dw_ced->ced);
dw_ced->ced.min_delta_ns = clockevent_delta2ns(5000, &dw_ced->ced);
dw_ced->ced.cpumask = cpumask_of(cpu);
- dw_ced->ced.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+ dw_ced->ced.features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ;
dw_ced->ced.set_state_shutdown = apbt_shutdown;
dw_ced->ced.set_state_periodic = apbt_set_periodic;
dw_ced->ced.set_state_oneshot = apbt_set_oneshot;