| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <1166578357.5594.3.camel@localhost>
Date: Tue, 19 Dec 2006 17:32:36 -0800
From: john stultz <johnstul@...ibm.com>
To: Roman Zippel <zippel@...ux-m68k.org>
Cc: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC] HZ free ntp
On Wed, 2006-12-13 at 21:40 +0100, Roman Zippel wrote:
> On Wed, 13 Dec 2006, john stultz wrote:
> > > You cannot choose arbitrary intervals otherwise you get other problems,
> > > e.g. with your patch time_offset handling is broken.
> >
> > I'm not seeing this yet. Any more details?
>
> time_offset is scaled to HZ in do_adjtimex, which needs to be changed as
> well.
Ah, thanks! Fixed.
> > > You don't have to introduce anything new, it's tick_length that changes
> > > and HZ that becomes a variable in this function.
> >
> > So, forgive me for rehashing this, but it seems we're cross talking
> > again. The context here is the dynticks code. Where HZ doesn't change,
> > but we get interrupts at much reduced rates.
>
> I know and all you have to change in the ntp and some related code is to
> replace HZ there with a variable, thus make it changable, so you can
> increase the update interval (i.e. it becomes 1s/hz instead of 1s/HZ).
Untested patch below. Does this vibe better with you are suggesting?
Any other suggestions or feedback?
thanks
-john
diff --git a/include/linux/timex.h b/include/linux/timex.h
index db501dc..8241e6e 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -286,6 +286,9 @@ #endif /* !CONFIG_TIME_INTERPOLATION */
#define TICK_LENGTH_SHIFT 32
+#define NTP_INTERVAL_FREQ (HZ)
+#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
+
/* Returns how long ticks are at present, in ns / 2^(SHIFT_SCALE-10). */
extern u64 current_tick_length(void);
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 3afeaa3..eb12509 100644
--- a/kernel/time/ntp.c
+++ b/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 @@ #define CLOCK_TICK_ADJUST (((s64)CLOCK_T
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);
}
/**
@@ -162,7 +166,7 @@ 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;
}
}
@@ -239,7 +243,8 @@ #endif
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) {
@@ -309,7 +314,8 @@ #endif
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)
@@ -324,8 +330,10 @@ 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;
diff --git a/kernel/timer.c b/kernel/timer.c
index 0256ab4..616b7fd 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -890,7 +890,7 @@ 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);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -1092,7 +1092,7 @@ #endif
if (change_clocksource()) {
clock->error = 0;
clock->xtime_nsec = 0;
- clocksource_calculate_interval(clock, tick_nsec);
+ clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
}
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists