Re: HZ value used in kernel/acct.c

[Ragnar Hojland Espinosa <ragnar@jazzfree.com>]

On Sun, Feb 24, 2002 at 10:35:33PM +0100, Tim Schmielau wrote:
> What is the supposed unit of the ac_etime field of struct acct?
> The code in kernel/acct.c currently says
> 
>    ac.ac_etime = encode_comp_t(jiffies - current->start_time);
> 
> so it is given in multiples of HZ, which makes this value 
> platform-dependent (and subject of overflow after 48.5 days with HZ=1024). 
> In include/linux/acct.h however there is the definition
> 
>    #define AHZ             100
> 
> which somehow smells like the preferred time unit.
> Comments?

The acct.c implementation followed FreeBSD's which also expressed comp_t
in terms platform dependant 1/(A)HZ   You could check the "[Patch] fix
incorrect jiffies compares" thread for a fix on uptime and 64 bit jiffies
someone sent.. didn't pay attention in why it didn't get in, tho.

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