time: remove xtime_cache (take 2)
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From: Andrew Morton on 13 Apr 2010 00:10 On Tue, 6 Apr 2010 14:30:51 -0700 John Stultz <johnstul(a)us.ibm.com> wrote: > Thomas: Mind queueing this up for 2.6.35? > > With the earlier logarithmic time accumulation patch, xtime will now > always be within one "tick" of the current time, instead of possibly > half a second off. > > This removes the need for the xtime_cache value, which always stored the > time at the last interrupt, so this patch cleans that up removing the > xtime_cache related code. > > This patch also addresses an issue with an earlier version of this change, > where xtime_cache was normalizing xtime, which could in some cases be > not valid (ie: tv_nsec == NSEC_PER_SEC). This is fixed by handling > the edge case in update_wall_time(). > > ... > > --- a/kernel/time.c > +++ b/kernel/time.c > @@ -135,7 +135,6 @@ static inline void warp_clock(void) > write_seqlock_irq(&xtime_lock); > wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60; > xtime.tv_sec += sys_tz.tz_minuteswest * 60; > - update_xtime_cache(0); > write_sequnlock_irq(&xtime_lock); > clock_was_set(); > } This conflicts with your time-clean-up-warp_clock.patch, below. Shrug, I simply ignored the rejected hunk. From: John Stultz <johnstul(a)us.ibm.com> warp_clock() currently accesses timekeeping internal state directly, which is unnecessary. Convert it to use the proper timekeeping interfaces. Signed-off-by: John Stultz <johnstul(a)us.ibm.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Ingo Molnar <mingo(a)elte.hu> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/time.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff -puN kernel/time.c~time-clean-up-warp_clock kernel/time.c --- a/kernel/time.c~time-clean-up-warp_clock +++ a/kernel/time.c @@ -132,12 +132,11 @@ SYSCALL_DEFINE2(gettimeofday, struct tim */ static inline void warp_clock(void) { - write_seqlock_irq(&xtime_lock); - wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60; - xtime.tv_sec += sys_tz.tz_minuteswest * 60; - update_xtime_cache(0); - write_sequnlock_irq(&xtime_lock); - clock_was_set(); + struct timespec delta, adjust; + delta.tv_sec = sys_tz.tz_minuteswest * 60; + delta.tv_nsec = 0; + adjust = timespec_add_safe(current_kernel_time(), delta); + do_settimeofday(&adjust); } /* _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: john stultz on 13 Apr 2010 00:10
On Mon, 2010-04-12 at 21:00 -0400, Andrew Morton wrote: > On Tue, 6 Apr 2010 14:30:51 -0700 John Stultz <johnstul(a)us.ibm.com> wrote: > > > Thomas: Mind queueing this up for 2.6.35? > > > > With the earlier logarithmic time accumulation patch, xtime will now > > always be within one "tick" of the current time, instead of possibly > > half a second off. > > > > This removes the need for the xtime_cache value, which always stored the > > time at the last interrupt, so this patch cleans that up removing the > > xtime_cache related code. > > > > This patch also addresses an issue with an earlier version of this change, > > where xtime_cache was normalizing xtime, which could in some cases be > > not valid (ie: tv_nsec == NSEC_PER_SEC). This is fixed by handling > > the edge case in update_wall_time(). > > > > ... > > > > --- a/kernel/time.c > > +++ b/kernel/time.c > > @@ -135,7 +135,6 @@ static inline void warp_clock(void) > > write_seqlock_irq(&xtime_lock); > > wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60; > > xtime.tv_sec += sys_tz.tz_minuteswest * 60; > > - update_xtime_cache(0); > > write_sequnlock_irq(&xtime_lock); > > clock_was_set(); > > } > > This conflicts with your time-clean-up-warp_clock.patch, below. > > Shrug, I simply ignored the rejected hunk. Yep. That should be fine. We're just dropping the update_xtime_cache call, so if it doesn't exist, its not a problem. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |