From e7e3ff1bfe9c42ee31172e9afdc0383a9e595e29 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Thu, 18 Jul 2013 16:21:17 -0700 Subject: sched_clock: Add support for >32 bit sched_clock The ARM architected system counter has at least 56 usable bits. Add support for counters with more than 32 bits to the generic sched_clock implementation so we can increase the time between wakeups due to dealing with wrap-around on these devices while benefiting from the irqtime accounting and suspend/resume handling that the generic sched_clock code already has. On my system using 56 bits over 32 bits changes the wraparound time from a few minutes to an hour. For faster running counters (GHz range) this is even more important because we may not be able to execute the timer in time to deal with the wraparound if only 32 bits are used. We choose a maxsec value of 3600 seconds because we assume no system will go idle for more than an hour. In the future we may need to increase this value. Note: All users should switch over to the 64-bit read function so we can remove setup_sched_clock() in favor of sched_clock_register(). Cc: Russell King Signed-off-by: Stephen Boyd Signed-off-by: John Stultz --- include/linux/sched_clock.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/sched_clock.h') diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h index fa7922c80a41..eca7abeb86fc 100644 --- a/include/linux/sched_clock.h +++ b/include/linux/sched_clock.h @@ -15,6 +15,8 @@ static inline void sched_clock_postinit(void) { } #endif extern void setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate); +extern void sched_clock_register(u64 (*read)(void), int bits, + unsigned long rate); extern unsigned long long (*sched_clock_func)(void); -- cgit v1.2.3 From b4042ceaabbd913bc5b397ddd1e396eeb312d72f Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Thu, 18 Jul 2013 16:21:19 -0700 Subject: sched_clock: Remove sched_clock_func() hook Nobody is using sched_clock_func() anymore now that sched_clock supports up to 64 bits. Remove the hook so that new code only uses sched_clock_register(). Signed-off-by: Stephen Boyd Signed-off-by: John Stultz --- include/linux/sched_clock.h | 2 -- kernel/time/sched_clock.c | 9 +-------- 2 files changed, 1 insertion(+), 10 deletions(-) (limited to 'include/linux/sched_clock.h') diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h index eca7abeb86fc..cddf0c2940b6 100644 --- a/include/linux/sched_clock.h +++ b/include/linux/sched_clock.h @@ -18,6 +18,4 @@ extern void setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate); extern void sched_clock_register(u64 (*read)(void), int bits, unsigned long rate); -extern unsigned long long (*sched_clock_func)(void); - #endif diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index f388baeaf2b6..68b799375981 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -63,7 +63,7 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift) return (cyc * mult) >> shift; } -static unsigned long long notrace sched_clock_32(void) +unsigned long long notrace sched_clock(void) { u64 epoch_ns; u64 epoch_cyc; @@ -170,13 +170,6 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) sched_clock_register(read_sched_clock_32_wrapper, bits, rate); } -unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32; - -unsigned long long notrace sched_clock(void) -{ - return sched_clock_func(); -} - void __init sched_clock_postinit(void) { /* -- cgit v1.2.3