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Date: Wed, 20 Feb 2002 13:36:02 +0200
From: Ville Herva <vherva@niksula.hut.fi>
To: george anzinger <george@mvista.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: jiffies rollover, uptime etc.
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On Tue, Feb 19, 2002 at 12:55:22PM -0800, you [george anzinger] wrote:
> > 
> > > Does this problem still exist on 64-bit machines?
> > 
> > Absolutely. But not as often ;-)
> 
> Actually you will have a VERY hard time getting it to roll over.  Issues
> of your life time, not to mention the hardware's life time.  64 bits
> makes a VERY large number and you are counting in 427 day increments. 
> Remember we have been counting seconds since 1970 in 32 bits and
> rollover is still, most likely, beyond the capability of any machine
> running today to get to.  Now consider counting in 427 day increments
> instead of seconds.

48.5 day increments, not 497. On alpha and ia64 it's 1024 jiffies per
second.

Well, ok. Majority of the 64-bit archs seem to in fact use HZ=100:

asm-alpha/param.h:#  define HZ  1024
asm-ia64/param.h:# define HZ    1024
asm-mips64/param.h:#define HZ 100
asm-ppc64/param.h:#define HZ 100
asm-s390x/param.h:#define HZ 100
asm-sparc64/param.h:#define HZ 100
asm-x86_64/param.h:#define HZ 100


-- v --

v@iki.fi
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