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* [PATCH] clocksource: riscv_timer: Provide sched_clock
@ 2018-12-03 12:35 Anup Patel
  2018-12-03 12:59 ` Daniel Lezcano
  2018-12-06 20:32 ` Palmer Dabbelt
  0 siblings, 2 replies; 6+ messages in thread
From: Anup Patel @ 2018-12-03 12:35 UTC (permalink / raw)
  To: Daniel Lezcano, Thomas Gleixner, Palmer Dabbelt, Albert Ou
  Cc: Christoph Hellwig, Atish Patra, linux-riscv, linux-kernel, Anup Patel

Currently, we don't have a sched_clock registered for RISC-V systems.
This means Linux time keeping will use jiffies (running at HZ) as the
default sched_clock.

To avoid this, we explicity provide sched_clock using RISC-V rdtime
instruction (similar to riscv_timer clocksource).

Signed-off-by: Anup Patel <anup@brainfault.org>
---
 drivers/clocksource/riscv_timer.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/clocksource/riscv_timer.c b/drivers/clocksource/riscv_timer.c
index 084e97dc10ed..431892200a08 100644
--- a/drivers/clocksource/riscv_timer.c
+++ b/drivers/clocksource/riscv_timer.c
@@ -8,6 +8,7 @@
 #include <linux/cpu.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
+#include <linux/sched_clock.h>
 #include <asm/smp.h>
 #include <asm/sbi.h>
 
@@ -49,6 +50,11 @@ static unsigned long long riscv_clocksource_rdtime(struct clocksource *cs)
 	return get_cycles64();
 }
 
+static u64 riscv_sched_clock(void)
+{
+	return get_cycles64();
+}
+
 static DEFINE_PER_CPU(struct clocksource, riscv_clocksource) = {
 	.name		= "riscv_clocksource",
 	.rating		= 300,
@@ -97,6 +103,9 @@ static int __init riscv_timer_init_dt(struct device_node *n)
 	cs = per_cpu_ptr(&riscv_clocksource, cpuid);
 	clocksource_register_hz(cs, riscv_timebase);
 
+	sched_clock_register(riscv_sched_clock,
+			BITS_PER_LONG, riscv_timebase);
+
 	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
 			 "clockevents/riscv/timer:starting",
 			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
-- 
2.17.1


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2018-12-03 12:35 [PATCH] clocksource: riscv_timer: Provide sched_clock Anup Patel
2018-12-03 12:59 ` Daniel Lezcano
2018-12-03 14:50   ` Anup Patel
2018-12-03 14:53     ` Daniel Lezcano
2018-12-06 20:32 ` Palmer Dabbelt
2018-12-07  2:27   ` Anup Patel

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