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List: linux-parisc
Subject: Re: invalid printk time during boot on PA-RISC
From: Helge Deller <deller () gmx ! de>
Date: 2016-06-14 21:23:35
Message-ID: 576075D7.60602 () gmx ! de
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Hi Mikulas,
On 14.06.2016 18:20, Mikulas Patocka wrote:
> There is another bug: when you enable CONFIG_DEBUG_TIMEKEEPING, parisc
> boot gets stuck with these messages.
Nice catch!
> (but it is not caused by the patch
> 54b668009076caddbede8fde513ca2c982590bfe, because this bug happens even in
> kernel 4.6).
Seems to be a generic upstream problem.
Would be nice to know if it happens on x86_64 as well.
I tried this patch (copy&pasted):
diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
index 31ec99a..85e7bb7 100644
--- a/arch/parisc/kernel/time.c
+++ b/arch/parisc/kernel/time.c
@@ -217,9 +217,16 @@ static struct clocksource clocksource_cr16 = {
.rating = 300,
.read = read_cr16,
.mask = CLOCKSOURCE_MASK(BITS_PER_LONG),
+ .mult = 1000,
+ .shift = 12,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
+struct clocksource * __init clocksource_default_clock(void)
+{
+ return &clocksource_cr16;
+}
+
int update_cr16_clocksource(void)
{
/* since the cr16 cycle counters are not synchronized across CPUs,
which gives:
[ 0.000000] clocksource: cr16: mask: 0xffffffff max_cycles: 0xffffffff, \
max_idle_ns: 29863444473 ns [ 0.000000] Console: colour dummy device 128x48
[ 0.012938] Calibrating delay loop... 63.07 BogoMIPS (lpj=315392)
[ 0.012938] pid_max: default: 32768 minimum: 301
[ 0.014235] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.014235] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.019359] Adjusting cr16 more than 11% (1000 vs -1967128576)
[ 0.019359] Brought up 1 CPUs
[ 0.020634] devtmpfs: initialized
[ 0.022716] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, \
max_idle_ns: 19112604462750000 ns [ 0.022716] NET: Registered protocol family 16
Still puzzled...
Helge
> Mikulas
>
> [ 0.000000] Memory: 7201556K/7337984K available (4096K kernel code, 1419K \
> rwdata, 883K rodata, 176K init, 2296K bss, 136428K reserved, 0K cma-reserved) [ \
> 0.000000] virtual kernel memory layout: [ 0.000000] vmalloc : \
> 0x0000000000008000 - 0x000000003f000000 (1007 MB) [ 0.000000] memory : \
> 0x0000000040000000 - 0x0000004140000000 (266240 MB) [ 0.000000] .init : \
> 0x0000000040100000 - 0x000000004012c000 ( 176 kB) [ 0.000000] .data : \
> 0x000000004052c000 - 0x000000004076bb60 (2302 kB) [ 0.000000] .text : \
> 0x000000004012c000 - 0x000000004052c000 (4096 kB) [ 0.000000] SLUB: \
> HWalign=16, Order=0-3, MinObjects=0, CPUs=4, Nodes=8 [ 0.000000] Hierarchical \
> RCU implementation. [ 0.000000] Build-time adjustment of leaf fanout to 64.
> [ 0.000000] NR_IRQS:80
> [ 0.000000] clocksource: cr16: mask: 0xffffffffffffffff max_cycles: \
> 0x1cd42e4dffb, max_idle_ns: 881590591483 ns [ 0.133333] WARNING: timekeeping: \
> Cycle offset (40) is larger than allowed by the 'jiffies' clock's max_cycles value \
> (10): time overflow danger [ 0.133333] timekeeping: Your kernel is \
> sick, but tries to cope by capping time updates [ 0.133333] Console: colour \
> dummy device 160x64 [ 0.303333] WARNING: timekeeping: Cycle offset (51) is \
> larger than allowed by the 'jiffies' clock's max_cycles value (10): time overflow \
> danger [ 0.303333] timekeeping: Your kernel is sick, but tries to cope \
> by capping time updates [ 0.423333] WARNING: timekeeping: Cycle offset (36) is \
> larger than allowed by the 'jiffies' clock's max_cycles value (10): time overflow \
> danger [ 0.423333] timekeeping: Your kernel is sick, but tries to cope \
> by capping time updates [ 0.483333] WARNING: timekeeping: Cycle offset (18) is \
> larger than allowed by the 'jiffies' clock's max_cycles value (10): time overflow \
> danger [ 0.483333] timekeeping: Your kernel is sick, but tries to cope \
> by capping time updates [ 0.653333] WARNING: timekeeping: Cycle offset (51) is \
> larger than allowed by the 'jiffies' clock's max_cycles value (10): time overflow \
> danger [ 0.653333] timekeeping: Your kernel is sick, but tries to cope \
> by capping time updates [ 0.769999] WARNING: timekeeping: Cycle offset (35) is \
> larger than allowed by the 'jiffies' clock's max_cycles value (10): time overflow \
> danger [ 0.769999] timekeeping: Your kernel is sick, but tries to cope \
> by capping time updates [ 0.943333] WARNING: timekeeping: Cycle offset (52) is \
> larger than allowed by the 'jiffies' clock's max_cycles value (10): time overflow \
> danger [ 0.943333] timekeeping: Your kernel is sick, but tries to cope \
> by capping time updates
>
> On Wed, 1 Jun 2016, Helge Deller wrote:
>
> > * Mikulas Patocka <mpatocka@redhat.com>:
> > > Hi
> > >
> > > With the kernel 4.7-rc1, I get corrupted printk times when the machine
> > > boots. The kernel is compiled with "Show timing information on printks"
> > > (CONFIG_PRINTK_TIME) enabled. There are no other negative effects.
> > >
> > > Bisecting shows that it is caused by the patch
> > > 54b668009076caddbede8fde513ca2c982590bfe ("parisc: Add native
> > > high-resolution sched_clock() implementation").
> > >
> > > [ 0.000000] NR_IRQS:80
> > > [ 0.000000] clocksource: cr16: mask: 0xffffffffffffffff max_cycles: \
> > > 0x1cd42e4dffb, max_idle_ns: 881590591483 ns [ 0.000000] Console: colour \
> > > dummy device 160x64 [ 90.122205] Calibrating delay loop... 1991.60 BogoMIPS \
> > > (lpj=3317760) [ 90.224168] pid_max: default: 32768 minimum: 301
> > > ....
> > > [ 92.235878] 13. Crestone Peak Core RS-232 at 0xfffffff0f05e2000 [18] { 10, \
> > > 0x0, 0x076, 0x000ad } [ 92.708000] Releasing cpu 1 now, hpa=fffffffffe781000
> > > [ 92.818803] FP[1] enabled: Rev 1 Model 20
> > > [ 2.917508] Releasing cpu 2 now, hpa=fffffffffe798000
> > > [ 0.196666] FP[2] enabled: Rev 1 Model 20
> > > [ 3.116794] Releasing cpu 3 now, hpa=fffffffffe799000
> > > [ 0.196666] FP[3] enabled: Rev 1 Model 20
> > > [ 3.296942] CPU(s): 4 out of 4 PA8900 (Shortfin) at 1000.000000 MHz online
> > > [ 3.447762] Setting cache flush threshold to 65536 kB
> > > [ 3.450548] Setting TLB flush threshold to 1020 kB
> >
> > Please try attached patch.
> >
> > It fixes the problem mostly for me, there is just one little glitch
> > left, which is that the lines "FP[x] enabled" will still print an
> > invalid time. I assume it's because when this text is printed, the
> > clock/interrupts for the just booted CPU aren't enabled yet.
> >
> > I'm not sure it's worth trying to fix that.
> > One could print out that info at a later time, or just disabled it.
> >
> > Helge
> >
> > [ 5.720014] Enabling PDC_PAT chassis codes support v0.05
> > [ 6.644542] Releasing cpu 1 now, hpa=fffffffffe781000
> > [ 0.196000] FP[1] enabled: Rev 1 Model 20
> > [ 7.088432] CPU(s): 2 out of 2 PA8800 (Mako) at 900.000000 MHz online
> >
> > -----------
> >
> > [PATCH] parisc: Fix printk time during boot
> >
> > Signed-off-by: Helge Deller <deller@gmx.de>
> >
> > diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
> > index 58dd680..31ec99a 100644
> > --- a/arch/parisc/kernel/time.c
> > +++ b/arch/parisc/kernel/time.c
> > @@ -309,11 +309,6 @@ void __init time_init(void)
> > clocks_calc_mult_shift(&cyc2ns_mul, &cyc2ns_shift, current_cr16_khz,
> > NSEC_PER_MSEC, 0);
> >
> > -#if defined(CONFIG_HAVE_UNSTABLE_SCHED_CLOCK) && defined(CONFIG_64BIT)
> > - /* At bootup only one 64bit CPU is online and cr16 is "stable" */
> > - set_sched_clock_stable();
> > -#endif
> > -
> > start_cpu_itimer(); /* get CPU 0 started */
> >
> > /* register at clocksource framework */
> >
--
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