The patch titled
exponential update_wall_time
has been added to the -mm tree. Its filename is
exponential-update_wall_time.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: exponential update_wall_time
From: john stultz <johnstul@xxxxxxxxxx>
Accumulate time in update_wall_time exponentially. This avoids long
running loops seen with the dynticks patch as well as the problematic hang"
seen on systems with broken clocksources.
Signed-off-by: John Stultz <johnstul@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/timer.c | 28 ++++++++++++++++++++--------
1 files changed, 20 insertions(+), 8 deletions(-)
diff -puN kernel/timer.c~exponential-update_wall_time kernel/timer.c
--- a/kernel/timer.c~exponential-update_wall_time
+++ a/kernel/timer.c
@@ -907,6 +907,7 @@ static void clocksource_adjust(struct cl
static void update_wall_time(void)
{
cycle_t offset;
+ int shift = 0;
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@@ -919,28 +920,39 @@ static void update_wall_time(void)
#endif
clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;
+ while (offset > clock->cycle_interval << (shift + 1))
+ shift++;
+
/* normally this loop will run just once, however in the
* case of lost or late ticks, it will accumulate correctly.
*/
while (offset >= clock->cycle_interval) {
+ if (offset < (clock->cycle_interval << shift)) {
+ shift--;
+ continue;
+ }
+
/* accumulate one interval */
- clock->xtime_nsec += clock->xtime_interval;
- clock->cycle_last += clock->cycle_interval;
- offset -= clock->cycle_interval;
+ clock->xtime_nsec += clock->xtime_interval << shift;
+ clock->cycle_last += clock->cycle_interval << shift;
+ offset -= clock->cycle_interval << shift;
- if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
+ while (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
xtime.tv_sec++;
second_overflow();
}
/* interpolator bits */
- time_interpolator_update(clock->xtime_interval
- >> clock->shift);
+ time_interpolator_update((clock->xtime_interval
+ >> clock->shift)<<shift);
/* accumulate error between NTP and clock interval */
- clock->error += current_tick_length();
- clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift);
+ clock->error += current_tick_length() << shift;
+ clock->error -= (clock->xtime_interval
+ << (TICK_LENGTH_SHIFT - clock->shift))<<shift;
+
+ shift--;
}
/* correct the clock when NTP error is too big */
_
Patches currently in -mm which might be from johnstul@xxxxxxxxxx are
origin.patch
simplify-update_times-avoid-jiffies-jiffies_64-aliasing-problem-2.patch
ntp-move-all-the-ntp-related-code-to-ntpc.patch
ntp-move-all-the-ntp-related-code-to-ntpc-fix.patch
ntp-add-ntp_update_frequency.patch
ntp-add-time_adj-to-tick-length.patch
ntp-add-time_freq-to-tick-length.patch
ntp-prescale-time_offset.patch
ntp-add-time_adjust-to-tick-length.patch
ntp-remove-time_tolerance.patch
ntp-convert-time_freq-to-nsec-value.patch
ntp-convert-to-the-ntp4-reference-model.patch
ntp-cleanup-defines-and-comments.patch
kernel-time-ntpc-possible-cleanups.patch
exponential-update_wall_time.patch
-
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