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authorStephen Boyd <sboyd@codeaurora.org>2013-07-19 03:21:17 +0400
committerJohn Stultz <john.stultz@linaro.org>2013-07-30 22:24:21 +0400
commite7e3ff1bfe9c42ee31172e9afdc0383a9e595e29 (patch)
tree3d3adc5cb561e0923947b7b200c29ddc79e050f5 /include/linux/sched_clock.h
parenta08ca5d1089da03724f96fa0870c64968e66765b (diff)
downloadlinux-e7e3ff1bfe9c42ee31172e9afdc0383a9e595e29.tar.xz
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 <linux@arm.linux.org.uk> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'include/linux/sched_clock.h')
-rw-r--r--include/linux/sched_clock.h2
1 files changed, 2 insertions, 0 deletions
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);