Messages in this thread Patch in this message | | | From | John Stultz <> | Subject | [PATCH 4/7] time: Update timekeeper structure using a local shadow | Date | Mon, 27 Feb 2012 16:29:31 -0800 |
| |
Uses a local shadow structure to update the timekeeper. This will allow for reduced timekeeper.rlock hold time.
CC: Thomas Gleixner <tglx@linutronix.de> CC: Eric Dumazet <eric.dumazet@gmail.com> CC: Richard Cochran <richardcochran@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org> --- kernel/time/timekeeping.c | 42 ++++++++++++++++++++++-------------------- 1 files changed, 22 insertions(+), 20 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 4962284..6c36d19 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1051,6 +1051,7 @@ static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset, static void update_wall_time(void) { struct clocksource *clock; + struct timekeeper tk; cycle_t offset; int shift = 0, maxshift; unsigned long flags; @@ -1063,10 +1064,11 @@ static void update_wall_time(void) if (unlikely(timekeeping_suspended)) goto out; - clock = timekeeper.clock; + tk = timekeeper; + clock = tk.clock; #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET - offset = timekeeper.cycle_interval; + offset = tk.cycle_interval; #else offset = (clock->read(clock) - clock->cycle_last) & clock->mask; #endif @@ -1079,19 +1081,19 @@ static void update_wall_time(void) * chunk in one go, and then try to consume the next smaller * doubled multiple. */ - shift = ilog2(offset) - ilog2(timekeeper.cycle_interval); + shift = ilog2(offset) - ilog2(tk.cycle_interval); shift = max(0, shift); /* Bound shift to one less then what overflows tick_length */ maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1; shift = min(shift, maxshift); - while (offset >= timekeeper.cycle_interval) { - offset = logarithmic_accumulation(&timekeeper, offset, shift); - if(offset < timekeeper.cycle_interval<<shift) + while (offset >= tk.cycle_interval) { + offset = logarithmic_accumulation(&tk, offset, shift); + if (offset < tk.cycle_interval<<shift) shift--; } /* correct the clock when NTP error is too big */ - timekeeping_adjust(&timekeeper, offset); + timekeeping_adjust(&tk, offset); /* * Since in the loop above, we accumulate any amount of time @@ -1109,10 +1111,10 @@ static void update_wall_time(void) * We'll correct this error next time through this function, when * xtime_nsec is not as small. */ - if (unlikely((s64)timekeeper.xtime_nsec < 0)) { - s64 neg = -(s64)timekeeper.xtime_nsec; - timekeeper.xtime_nsec = 0; - timekeeper.ntp_error += neg << timekeeper.ntp_error_shift; + if (unlikely((s64)tk.xtime_nsec < 0)) { + s64 neg = -(s64)tk.xtime_nsec; + tk.xtime_nsec = 0; + tk.ntp_error += neg << tk.ntp_error_shift; } /* @@ -1124,23 +1126,23 @@ static void update_wall_time(void) * the vsyscall implementations are converted to use xtime_nsec * (shifted nanoseconds), this can be killed. */ - remainder = timekeeper.xtime_nsec & ((1<<timekeeper.shift)-1); - timekeeper.xtime_nsec -= remainder; - timekeeper.xtime_nsec += 1<<timekeeper.shift; - timekeeper.ntp_error += remainder << - timekeeper.ntp_error_shift; + remainder = tk.xtime_nsec & ((1<<tk.shift)-1); + tk.xtime_nsec -= remainder; + tk.xtime_nsec += 1<<tk.shift; + tk.ntp_error += remainder << tk.ntp_error_shift; /* * Finally, make sure that after the rounding * xtime.tv_nsec isn't larger then NSEC_PER_SEC */ - if (unlikely(timekeeper.xtime_nsec >= - (NSEC_PER_SEC << timekeeper.shift))) { - timekeeper.xtime_nsec -= NSEC_PER_SEC << timekeeper.shift; - timekeeper.xtime_sec++; + if (unlikely(tk.xtime_nsec >= (NSEC_PER_SEC << tk.shift))) { + tk.xtime_nsec -= NSEC_PER_SEC << tk.shift; + tk.xtime_sec++; second_overflow(); } + + timekeeper = tk; timekeeping_update(&timekeeper, false); out: -- 1.7.3.2.146.gca209
| |