2014-07-11 13:44:04

by Thomas Gleixner

Subject: [patch 01/55] tile: Convert VDSO timekeeping to the precise mechanism

The code was only halfarsed converted to the new VSDO update mechanism
and still uses the inaccurate base value which lacks the fractional
part of xtime_nsec. Fix it up.

Signed-off-by: Thomas Gleixner <[email protected]>
---
arch/tile/kernel/time.c | 9 ++++-----
arch/tile/kernel/vdso/vgettimeofday.c | 7 ++++---
2 files changed, 8 insertions(+), 8 deletions(-)

Index: tip/arch/tile/kernel/time.c
===================================================================
--- tip.orig/arch/tile/kernel/time.c
+++ tip/arch/tile/kernel/time.c
@@ -260,7 +260,6 @@ void update_vsyscall_tz(void)

void update_vsyscall(struct timekeeper *tk)
{
- struct timespec wall_time = tk_xtime(tk);
struct timespec *wtm = &tk->wall_to_monotonic;
struct clocksource *clock = tk->clock;

@@ -271,12 +270,12 @@ void update_vsyscall(struct timekeeper *
++vdso_data->tb_update_count;
smp_wmb();
vdso_data->xtime_tod_stamp = clock->cycle_last;
- vdso_data->xtime_clock_sec = wall_time.tv_sec;
- vdso_data->xtime_clock_nsec = wall_time.tv_nsec;
+ vdso_data->xtime_clock_sec = tk->xtime_sec;
+ vdso_data->xtime_clock_nsec = tk->xtime_nsec;
vdso_data->wtom_clock_sec = wtm->tv_sec;
vdso_data->wtom_clock_nsec = wtm->tv_nsec;
- vdso_data->mult = clock->mult;
- vdso_data->shift = clock->shift;
+ vdso_data->mult = tk->mult;
+ vdso_data->shift = tk->shift;
smp_wmb();
++vdso_data->tb_update_count;
}
Index: tip/arch/tile/kernel/vdso/vgettimeofday.c
===================================================================
--- tip.orig/arch/tile/kernel/vdso/vgettimeofday.c
+++ tip/arch/tile/kernel/vdso/vgettimeofday.c
@@ -83,10 +83,11 @@ int __vdso_gettimeofday(struct timeval *
if (count & 1)
continue;

- cycles = (get_cycles() - vdso_data->xtime_tod_stamp);
- ns = (cycles * vdso_data->mult) >> vdso_data->shift;
sec = vdso_data->xtime_clock_sec;
- ns += vdso_data->xtime_clock_nsec;
+ cycles = get_cycles() - vdso_data->xtime_tod_stamp;
+ ns = (cycles * vdso_data->mult) + vdso_data->xtime_clock_nsec;
+ ns >>= vdso_data->shift;
+
if (ns >= NSEC_PER_SEC) {
ns -= NSEC_PER_SEC;
sec += 1;

2014-07-18 02:32:16

by Chris Metcalf

Subject: Re: [patch 01/55] tile: Convert VDSO timekeeping to the precise mechanism

On 7/11/2014 9:45 AM, Thomas Gleixner wrote:
> The code was only halfarsed converted to the new VSDO update mechanism
> and still uses the inaccurate base value which lacks the fractional
> part of xtime_nsec. Fix it up.
>
> Signed-off-by: Thomas Gleixner<[email protected]>
> ---
> arch/tile/kernel/time.c | 9 ++++-----
> arch/tile/kernel/vdso/vgettimeofday.c | 7 ++++---
> 2 files changed, 8 insertions(+), 8 deletions(-)

Acked-by: Chris Metcalf <[email protected]>

--
Chris Metcalf, Tilera Corp.
http://www.tilera.com