diff options
| author | Bharat Bhushan <r65777@freescale.com> | 2012-04-18 06:01:19 +0000 |
|---|---|---|
| committer | Alexander Graf <agraf@suse.de> | 2012-05-06 16:19:07 +0200 |
| commit | 6e35994d1f6831af1e5577e28c363c9137d7d597 (patch) | |
| tree | 4c230223e9f76865a2bf01e4f4893b30fe2482b7 /arch/powerpc/include/asm/time.h | |
| parent | cc902ad4f2b7cd3dd2cc268c63f6fb99fb1abf0f (diff) | |
KVM: PPC: Use clockevent multiplier and shifter for decrementer
Time for which the hrtimer is started for decrementer emulation is calculated
using tb_ticks_per_usec. While hrtimer uses the clockevent for DEC
reprogramming (if needed) and which calculate timebase ticks using the
multiplier and shifter mechanism implemented within clockevent layer.
It was observed that this conversion (timebase->time->timebase) are not
correct because the mechanism are not consistent.
In our setup it adds 2% jitter.
With this patch clockevent multiplier and shifter mechanism are used when
starting hrtimer for decrementer emulation. Now the jitter is < 0.5%.
Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/include/asm/time.h')
| -rw-r--r-- | arch/powerpc/include/asm/time.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 2136f58a54e8..3b4b4a8da922 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -23,6 +23,7 @@ extern unsigned long tb_ticks_per_jiffy; extern unsigned long tb_ticks_per_usec; extern unsigned long tb_ticks_per_sec; +extern struct clock_event_device decrementer_clockevent; struct rtc_time; extern void to_tm(int tim, struct rtc_time * tm); |