Re: HZ value used in kernel/acct.c

From: Ragnar Hojland Espinosa (ragnar@jazzfree.com)
Date: Mon Feb 25 2002 - 15:44:37 EST

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. 

-- 
____/|  Ragnar Højland      Freedom - Linux - OpenGL |    Brainbench MVP
\ o.O|  PGP94C4B2F0D27DE025BE2302C104B78C56 B72F0822 | for Unix Programming
 =(_)=  "Thou shalt not follow the NULL pointer for  | (www.brainbench.com)
   U     chaos and madness await thee at its end."      [20 pend. Mar 10]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

This archive was generated by hypermail 2b29 : Thu Feb 28 2002 - 21:00:18 EST