Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932785AbWCRAlJ (ORCPT ); Fri, 17 Mar 2006 19:41:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932822AbWCRAkm (ORCPT ); Fri, 17 Mar 2006 19:40:42 -0500 Received: from e36.co.us.ibm.com ([32.97.110.154]:25295 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S932785AbWCRAkW (ORCPT ); Fri, 17 Mar 2006 19:40:22 -0500 Date: Fri, 17 Mar 2006 17:40:21 -0700 From: john stultz To: lkml Cc: john stultz , george@wildturkeyranch.net, Steven Rostedt , Thomas Gleixner , Ulrich Windl , Roman Zippel , Ingo Molnar Message-Id: <20060318004020.32251.87158.sendpatchset@cog.beaverton.ibm.com> In-Reply-To: <20060318003955.32251.80532.sendpatchset@cog.beaverton.ibm.com> References: <20060318003955.32251.80532.sendpatchset@cog.beaverton.ibm.com> Subject: [PATCH 4/10] Time: Use clocksource abstraction for NTP adjustments Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4090 Lines: 115 Instead of incrementing xtime by tick_nsec + ntp adjustments, use the clocksource abstraction. This removes the need to keep time_phase adjustments as we just use the current_tick_length() function and accumulate using shifted nanoseconds. By using the clocksource abstraction to increment time, this allows other clocksources to be used consistently in the face of late or lost ticks, while preserving the existing behavior via the jiffies clocksource. Signed-off-by: John Stultz timer.c | 49 ++++++++++++++++++++++++++++++------------------- 1 files changed, 30 insertions(+), 19 deletions(-) linux-2.6.16-rc6_timeofday-core3_C0.patch ============================================ diff --git a/kernel/timer.c b/kernel/timer.c index 90fe137..99b6c83 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -599,7 +599,6 @@ long time_tolerance = MAXFREQ; /* frequ long time_precision = 1; /* clock precision (us) */ long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */ long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ -static long time_phase; /* phase offset (scaled us) */ long time_freq = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC; /* frequency offset (scaled ppm)*/ static long time_adj; /* tick adjust (scaled 1 / HZ) */ @@ -758,27 +757,14 @@ static long adjtime_adjustment(void) } /* in the NTP reference this is called "hardclock()" */ -static void update_wall_time_one_tick(void) +static void update_ntp_one_tick(void) { - long time_adjust_step, delta_nsec; + long time_adjust_step; time_adjust_step = adjtime_adjustment(); if (time_adjust_step) /* Reduce by this step the amount of time left */ time_adjust -= time_adjust_step; - delta_nsec = tick_nsec + time_adjust_step * 1000; - /* - * Advance the phase, once it gets to one microsecond, then - * advance the tick more. - */ - time_phase += time_adj; - if ((time_phase >= FINENSEC) || (time_phase <= -FINENSEC)) { - long ltemp = shift_right(time_phase, (SHIFT_SCALE - 10)); - time_phase -= ltemp << (SHIFT_SCALE - 10); - delta_nsec += ltemp; - } - xtime.tv_nsec += delta_nsec; - time_interpolator_update(delta_nsec); /* Changes by adjtime() do not take effect till next tick. */ if (time_next_adjust != 0) { @@ -883,8 +869,13 @@ device_initcall(timekeeping_init_device) */ static void update_wall_time(void) { + static s64 remainder_snsecs, error; + s64 snsecs_per_sec; cycle_t now, offset; + snsecs_per_sec = (s64)NSEC_PER_SEC << clock->shift; + remainder_snsecs += (s64)xtime.tv_nsec << clock->shift; + now = read_clocksource(clock); offset = (now - last_clock_cycle)&clock->mask; @@ -892,13 +883,33 @@ static void update_wall_time(void) * case of lost or late ticks, it will accumulate correctly. */ while (offset > clock->interval_cycles) { - update_wall_time_one_tick(); - if (xtime.tv_nsec >= 1000000000) { - xtime.tv_nsec -= 1000000000; + s64 ntp_snsecs = current_tick_length(clock->shift); + + /* increment the last cycle, offset and remainder snsec vals */ + last_clock_cycle += clock->interval_cycles; + offset -= clock->interval_cycles; + remainder_snsecs += clock->interval_snsecs; + + /* accumulate error between NTP and clock tick interval */ + error += (ntp_snsecs - (s64)clock->interval_snsecs); + + /* interpolator bits */ + time_interpolator_update(clock->interval_snsecs + >> clock->shift); + + update_ntp_one_tick(); + + /* correct the clock when NTP error is too big */ + remainder_snsecs += make_ntp_adj(clock, offset, &error); + + if (remainder_snsecs >= snsecs_per_sec) { + remainder_snsecs -= snsecs_per_sec; xtime.tv_sec++; second_overflow(); } } + xtime.tv_nsec = remainder_snsecs >> clock->shift; + remainder_snsecs -= (s64)xtime.tv_nsec << clock->shift; } /* - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/