From 0a54419836254a27baecd9037103171bcbabaf67 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 14 Aug 2009 15:47:28 +0200 Subject: [PATCH] timekeeping: Move NTP adjusted clock multiplier to struct timekeeper The clocksource structure has two multipliers, the unmodified multiplier clock->mult_orig and the NTP corrected multiplier clock->mult. The NTP multiplier is misplaced in the struct clocksource, this is private information of the timekeeping code. Add the mult field to the struct timekeeper to contain the NTP corrected value, keep the unmodifed multiplier in clock->mult and remove clock->mult_orig. Signed-off-by: Martin Schwidefsky Cc: Ingo Molnar Acked-by: John Stultz Cc: Daniel Walker LKML-Reference: <20090814134810.149047645@de.ibm.com> Signed-off-by: Thomas Gleixner --- arch/arm/plat-omap/common.c | 7 ++--- include/linux/clocksource.h | 4 +-- kernel/time/timekeeping.c | 53 +++++++++++++++++-------------------- 3 files changed, 27 insertions(+), 37 deletions(-) diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c index ebcf006406f9..95587b6c0259 100644 --- a/arch/arm/plat-omap/common.c +++ b/arch/arm/plat-omap/common.c @@ -253,11 +253,8 @@ static struct clocksource clocksource_32k = { */ unsigned long long sched_clock(void) { - unsigned long long ret; - - ret = (unsigned long long)clocksource_32k.read(&clocksource_32k); - ret = (ret * clocksource_32k.mult_orig) >> clocksource_32k.shift; - return ret; + return clocksource_cyc2ns(clocksource_32k.read(&clocksource_32k), + clocksource_32k.mult, clocksource_32k.shift); } static int __init omap_init_clocksource_32k(void) diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index e12e3095e2fb..e34015effeb6 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -149,8 +149,7 @@ extern u64 timecounter_cyc2time(struct timecounter *tc, * @disable: optional function to disable the clocksource * @mask: bitmask for two's complement * subtraction of non 64 bit counters - * @mult: cycle to nanosecond multiplier (adjusted by NTP) - * @mult_orig: cycle to nanosecond multiplier (unadjusted by NTP) + * @mult: cycle to nanosecond multiplier * @shift: cycle to nanosecond divisor (power of two) * @flags: flags describing special properties * @vread: vsyscall based read @@ -168,7 +167,6 @@ struct clocksource { void (*disable)(struct clocksource *cs); cycle_t mask; u32 mult; - u32 mult_orig; u32 shift; unsigned long flags; cycle_t (*vread)(void); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index dfdab1cefe1e..f4056f6c2632 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -41,6 +41,8 @@ struct timekeeper { /* Shift conversion between clock shifted nano seconds and * ntp shifted nano seconds. */ int ntp_error_shift; + /* NTP adjusted clock multiplier */ + u32 mult; }; struct timekeeper timekeeper; @@ -66,8 +68,8 @@ static void timekeeper_setup_internals(struct clocksource *clock) /* Do the ns -> cycle conversion first, using original mult */ tmp = NTP_INTERVAL_LENGTH; tmp <<= clock->shift; - tmp += clock->mult_orig/2; - do_div(tmp, clock->mult_orig); + tmp += clock->mult/2; + do_div(tmp, clock->mult); if (tmp == 0) tmp = 1; @@ -77,13 +79,20 @@ static void timekeeper_setup_internals(struct clocksource *clock) /* Go back from cycles -> shifted ns */ timekeeper.xtime_interval = (u64) interval * clock->mult; timekeeper.raw_interval = - ((u64) interval * clock->mult_orig) >> clock->shift; + ((u64) interval * clock->mult) >> clock->shift; timekeeper.xtime_nsec = 0; timekeeper.shift = clock->shift; timekeeper.ntp_error = 0; timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; + + /* + * The timekeeper keeps its own mult values for the currently + * active clocksource. These value will be adjusted via NTP + * to counteract clock drifting. + */ + timekeeper.mult = clock->mult; } /* @@ -154,14 +163,15 @@ static void timekeeping_forward_now(void) cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; clock->cycle_last = cycle_now; - nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); + nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult, + timekeeper.shift); /* If arch requires, add in gettimeoffset() */ nsec += arch_gettimeoffset(); timespec_add_ns(&xtime, nsec); - nsec = clocksource_cyc2ns(cycle_delta, clock->mult_orig, clock->shift); + nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); timespec_add_ns(&raw_time, nsec); } @@ -193,8 +203,8 @@ void getnstimeofday(struct timespec *ts) cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* convert to nanoseconds: */ - nsecs = clocksource_cyc2ns(cycle_delta, clock->mult, - clock->shift); + nsecs = clocksource_cyc2ns(cycle_delta, timekeeper.mult, + timekeeper.shift); /* If arch requires, add in gettimeoffset() */ nsecs += arch_gettimeoffset(); @@ -228,8 +238,8 @@ ktime_t ktime_get(void) cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* convert to nanoseconds: */ - nsecs += clocksource_cyc2ns(cycle_delta, clock->mult, - clock->shift); + nsecs += clocksource_cyc2ns(cycle_delta, timekeeper.mult, + timekeeper.shift); } while (read_seqretry(&xtime_lock, seq)); /* @@ -271,8 +281,8 @@ void ktime_get_ts(struct timespec *ts) cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* convert to nanoseconds: */ - nsecs = clocksource_cyc2ns(cycle_delta, clock->mult, - clock->shift); + nsecs = clocksource_cyc2ns(cycle_delta, timekeeper.mult, + timekeeper.shift); } while (read_seqretry(&xtime_lock, seq)); @@ -356,22 +366,10 @@ static void change_clocksource(void) if (new->enable && !new->enable(new)) return; - /* - * The frequency may have changed while the clocksource - * was disabled. If so the code in ->enable() must update - * the mult value to reflect the new frequency. Make sure - * mult_orig follows this change. - */ - new->mult_orig = new->mult; old = timekeeper.clock; timekeeper_setup_internals(new); - /* - * Save mult_orig in mult so that the value can be restored - * regardless if ->enable() updates the value of mult or not. - */ - old->mult = old->mult_orig; if (old->disable) old->disable(old); @@ -461,7 +459,7 @@ void getrawmonotonic(struct timespec *ts) cycle_delta = (cycle_now - clock->cycle_last) & clock->mask; /* convert to nanoseconds: */ - nsecs = clocksource_cyc2ns(cycle_delta, clock->mult_orig, + nsecs = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift); *ts = raw_time; @@ -521,9 +519,6 @@ void __init timekeeping_init(void) clock = clocksource_default_clock(); if (clock->enable) clock->enable(clock); - /* set mult_orig on enable */ - clock->mult_orig = clock->mult; - timekeeper_setup_internals(clock); xtime.tv_sec = sec; @@ -697,7 +692,7 @@ static void timekeeping_adjust(s64 offset) } else return; - timekeeper.clock->mult += adj; + timekeeper.mult += adj; timekeeper.xtime_interval += interval; timekeeper.xtime_nsec -= offset; timekeeper.ntp_error -= (interval - offset) << @@ -789,7 +784,7 @@ void update_wall_time(void) timekeeper.ntp_error += timekeeper.xtime_nsec << timekeeper.ntp_error_shift; - nsecs = clocksource_cyc2ns(offset, clock->mult, clock->shift); + nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift); update_xtime_cache(nsecs); /* check to see if there is a new clocksource to use */