Messages in this thread | | | Date | Tue, 6 Jan 2004 17:30:39 +0100 (CET) | From | Tim Schmielau <> | Subject | Re: [PATCH] fix get_jiffies_64 to work on voyager |
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On Tue, 6 Jan 2004, Andrew Morton wrote:
> James Bottomley <James.Bottomley@SteelEye.com> wrote: > > > > This patch > > > > > > ChangeSet@1.1534.5.2, 2003-12-30 15:40:23-08:00, akpm@osdl.org > > [PATCH] ia32 jiffy wrapping fixes > > > > Causes the voyager boot to hang. The problem is this change: > > > > --- a/arch/i386/kernel/timers/timer_tsc.c Tue Jan 6 09:57:34 2004 > > +++ b/arch/i386/kernel/timers/timer_tsc.c Tue Jan 6 09:57:34 2004 > > @@ -141,7 +140,7 @@ > > #ifndef CONFIG_NUMA > > if (!use_tsc) > > #endif > > - return (unsigned long long)jiffies * (1000000000 / HZ); > > + return (unsigned long long)get_jiffies_64() * > > (1000000000 / HZ); > > Hm, OK. I hit the same deadlock when running with the "don't require TSCs > to be synchronised in sched_clock()" patch from -mm. The fix for that is > below. I shall accelerate it. > > --- 25/arch/i386/kernel/timers/timer_tsc.c~sched_clock-2.6.0-A1-deadlock-fix 2003-12-30 00:45:09.000000000 -0800 > +++ 25-akpm/arch/i386/kernel/timers/timer_tsc.c 2003-12-30 00:45:09.000000000 -0800 > @@ -140,7 +140,8 @@ unsigned long long sched_clock(void) > #ifndef CONFIG_NUMA > if (!use_tsc) > #endif > - return (unsigned long long)get_jiffies_64() * (1000000000 / HZ); > + /* jiffies might overflow but this is not a big deal here */ > + return (unsigned long long)jiffies * (1000000000 / HZ); > > /* Read the Time Stamp Counter */ > rdtscll(this_offset);
Yes, please revert that change. When I tested it, I didn't realize I need NUMA or clear use_tsc to actually cover the change. And it's indeed not a big deal.
The proposed get_jiffies_64() change however looks quite fragile to me.
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