Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751868AbXAVT2l (ORCPT ); Mon, 22 Jan 2007 14:28:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751959AbXAVT2l (ORCPT ); Mon, 22 Jan 2007 14:28:41 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:57486 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751868AbXAVT2j (ORCPT ); Mon, 22 Jan 2007 14:28:39 -0500 Date: Mon, 22 Jan 2007 20:27:12 +0100 From: Ingo Molnar To: john stultz Cc: Roman Zippel , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org Subject: [patch] HZ-free NTP Message-ID: <20070122192712.GC12911@elte.hu> References: <1165393929.24604.222.camel@localhost.localdomain> <20061206131155.GA8558@elte.hu> <1165956021.20229.10.camel@localhost> <1166037549.6425.21.camel@localhost.localdomain> <1166578357.5594.3.camel@localhost> <1166579658.5594.6.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1166579658.5594.6.camel@localhost> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -4.3 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-4.3 required=5.9 tests=ALL_TRUSTED,BAYES_00,UPPERCASE_25_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -1.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] 0.0 UPPERCASE_25_50 message body is 25-50% uppercase Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5812 Lines: 169 * john stultz wrote: > And here would be the follow on patch (again *untested*) for > CONFIG_NO_HZ slowing the time accumulation down to once per second. thanks John - i've applied the combined patch below to -rt. It appears to work fine for me. Ingo ------------------------> From: John Stultz Subject: [patch] HZ-free NTP Basically INTERVAL_LENGTH_NSEC defines the NTP interval length that the time code will use to accumulate with. In this patch I've pushed it out to a full second, but it could be set via config (NSEC_PER_SEC/HZ for regular systems, something larger for systems using dynticks). Signed-off-by: Ingo Molnar --- include/linux/timex.h | 4 ++++ kernel/hrtimer.c | 4 +++- kernel/time/ntp.c | 30 +++++++++++++++++++----------- kernel/timer.c | 4 ++-- 4 files changed, 28 insertions(+), 14 deletions(-) Index: linux/include/linux/timex.h =================================================================== --- linux.orig/include/linux/timex.h +++ linux/include/linux/timex.h @@ -286,7 +286,11 @@ static inline void time_interpolator_upd #define TICK_LENGTH_SHIFT 32 +#ifdef CONFIG_NO_HZ +#define NTP_INTERVAL_FREQ (1) +#else #define NTP_INTERVAL_FREQ (HZ) +#endif #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ) /* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */ Index: linux/kernel/hrtimer.c =================================================================== --- linux.orig/kernel/hrtimer.c +++ linux/kernel/hrtimer.c @@ -135,12 +135,14 @@ EXPORT_SYMBOL_GPL(ktime_get_ts); */ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base) { + struct timespec ts; ktime_t xtim, tomono; unsigned long seq; do { seq = read_seqbegin(&xtime_lock); - xtim = timespec_to_ktime(xtime); + getnstimeofday(&ts); + xtim = timespec_to_ktime(ts); tomono = timespec_to_ktime(wall_to_monotonic); } while (read_seqretry(&xtime_lock, seq)); Index: linux/kernel/time/ntp.c =================================================================== --- linux.orig/kernel/time/ntp.c +++ linux/kernel/time/ntp.c @@ -24,7 +24,7 @@ static u64 tick_length, tick_length_base #define MAX_TICKADJ 500 /* microsecs */ #define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \ - TICK_LENGTH_SHIFT) / HZ) + TICK_LENGTH_SHIFT) / NTP_INTERVAL_FREQ) /* * phase-lock loop variables @@ -46,13 +46,17 @@ long time_adjust; static void ntp_update_frequency(void) { - tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT; - tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT; - tick_length_base += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC); + u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) + << TICK_LENGTH_SHIFT; + second_length += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT; + second_length += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC); - do_div(tick_length_base, HZ); + tick_length_base = second_length; - tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT; + do_div(second_length, HZ); + tick_nsec = second_length >> TICK_LENGTH_SHIFT; + + do_div(tick_length_base, NTP_INTERVAL_FREQ); } /** @@ -164,7 +168,7 @@ void second_overflow(void) tick_length -= MAX_TICKADJ_SCALED; } else { tick_length += (s64)(time_adjust * NSEC_PER_USEC / - HZ) << TICK_LENGTH_SHIFT; + NTP_INTERVAL_FREQ) << TICK_LENGTH_SHIFT; time_adjust = 0; } } @@ -241,7 +245,8 @@ int do_adjtimex(struct timex *txc) result = -EINVAL; goto leave; } - time_freq = ((s64)txc->freq * NSEC_PER_USEC) >> (SHIFT_USEC - SHIFT_NSEC); + time_freq = ((s64)txc->freq * NSEC_PER_USEC) + >> (SHIFT_USEC - SHIFT_NSEC); } if (txc->modes & ADJ_MAXERROR) { @@ -311,7 +316,8 @@ int do_adjtimex(struct timex *txc) freq_adj += time_freq; freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC); time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC); - time_offset = (time_offset / HZ) << SHIFT_UPDATE; + time_offset = (time_offset / NTP_INTERVAL_FREQ) + << SHIFT_UPDATE; } /* STA_PLL */ } /* txc->modes & ADJ_OFFSET */ if (txc->modes & ADJ_TICK) @@ -326,8 +332,10 @@ leave: if ((time_status & (STA_UNSYNC|ST if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) txc->offset = save_adjust; else - txc->offset = shift_right(time_offset, SHIFT_UPDATE) * HZ / 1000; - txc->freq = (time_freq / NSEC_PER_USEC) << (SHIFT_USEC - SHIFT_NSEC); + txc->offset = shift_right(time_offset, SHIFT_UPDATE) + * NTP_INTERVAL_FREQ / 1000; + txc->freq = (time_freq / NSEC_PER_USEC) + << (SHIFT_USEC - SHIFT_NSEC); txc->maxerror = time_maxerror; txc->esterror = time_esterror; txc->status = time_status; Index: linux/kernel/timer.c =================================================================== --- linux.orig/kernel/timer.c +++ linux/kernel/timer.c @@ -1030,7 +1030,7 @@ static void change_clocksource(void) clock->error = 0; clock->xtime_nsec = 0; - clocksource_calculate_interval(clock, tick_nsec); + clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH); tick_clock_notify(); @@ -1086,7 +1086,7 @@ void __init timekeeping_init(void) ntp_clear(); clock = clocksource_get_next(); - clocksource_calculate_interval(clock, tick_nsec); + clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH); clock->cycle_last = clocksource_read(clock); xtime.tv_sec = sec; - 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/