diff options
author | Marcelo Tosatti <mtosatti@redhat.com> | 2012-10-29 19:15:32 -0200 |
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committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-10-29 19:15:32 -0200 |
commit | 19bf7f8ac3f8131100027281c495dbbe00cd5ae0 (patch) | |
tree | 270b97e3ca47c0f62a1babca2ae37f79a76a309c /kernel/time/jiffies.c | |
parent | 787c57c0fb393fe8a3974d300ddcfe30373386fe (diff) | |
parent | 35fd3dc58da675d659513384221349ef90749a01 (diff) |
Merge remote-tracking branch 'master' into queue
Merge reason: development work has dependency on kvm patches merged
upstream.
Conflicts:
arch/powerpc/include/asm/Kbuild
arch/powerpc/include/asm/kvm_para.h
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'kernel/time/jiffies.c')
-rw-r--r-- | kernel/time/jiffies.c | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index 46da0537c10..6629bf7b528 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -37,7 +37,7 @@ * requested HZ value. It is also not recommended * for "tick-less" systems. */ -#define NSEC_PER_JIFFY ((u32)((((u64)NSEC_PER_SEC)<<8)/SHIFTED_HZ)) +#define NSEC_PER_JIFFY ((NSEC_PER_SEC+HZ/2)/HZ) /* Since jiffies uses a simple NSEC_PER_JIFFY multiplier * conversion, the .shift value could be zero. However @@ -95,3 +95,33 @@ struct clocksource * __init __weak clocksource_default_clock(void) { return &clocksource_jiffies; } + +struct clocksource refined_jiffies; + +int register_refined_jiffies(long cycles_per_second) +{ + u64 nsec_per_tick, shift_hz; + long cycles_per_tick; + + + + refined_jiffies = clocksource_jiffies; + refined_jiffies.name = "refined-jiffies"; + refined_jiffies.rating++; + + /* Calc cycles per tick */ + cycles_per_tick = (cycles_per_second + HZ/2)/HZ; + /* shift_hz stores hz<<8 for extra accuracy */ + shift_hz = (u64)cycles_per_second << 8; + shift_hz += cycles_per_tick/2; + do_div(shift_hz, cycles_per_tick); + /* Calculate nsec_per_tick using shift_hz */ + nsec_per_tick = (u64)NSEC_PER_SEC << 8; + nsec_per_tick += (u32)shift_hz/2; + do_div(nsec_per_tick, (u32)shift_hz); + + refined_jiffies.mult = ((u32)nsec_per_tick) << JIFFIES_SHIFT; + + clocksource_register(&refined_jiffies); + return 0; +} |