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Re: MSEC_TO_JIFFIES is messed up...

To: Andrew Morton <akpm@xxxxxxxx>
Subject: Re: MSEC_TO_JIFFIES is messed up...
From: William Lee Irwin III <wli@xxxxxxxxxxxxxx>
Date: Wed, 12 May 2004 13:38:29 -0700
Cc: Ingo Molnar <mingo@xxxxxxx>, davidel@xxxxxxxxxxxxxxx, jgarzik@xxxxxxxxx, greg@xxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <20040512132050.6eae6905.akpm@osdl.org>
Mail-followup-to: William Lee Irwin III <wli@xxxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>, davidel@xxxxxxxxxxxxxxx, jgarzik@xxxxxxxxx, greg@xxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxx
References: <20040512020700.6f6aa61f.akpm@osdl.org> <20040512181903.GG13421@kroah.com> <40A26FFA.4030701@pobox.com> <20040512193349.GA14936@elte.hu> <Pine.LNX.4.58.0405121247011.11950@bigblue.dev.mdolabs.com> <20040512200305.GA16078@elte.hu> <20040512132050.6eae6905.akpm@osdl.org>
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On Wed, May 12, 2004 at 01:20:50PM -0700, Andrew Morton wrote:
> How about we do:
> #if HZ=1000
> #define       MSEC_TO_JIFFIES(msec) (msec)
> #define JIFFIES_TO_MESC(jiffies) (jiffies)
> #elif HZ=100
> #define       MSEC_TO_JIFFIES(msec) (msec * 10)
> #define JIFFIES_TO_MESC(jiffies) (jiffies / 10)
> #else
> #define       MSEC_TO_JIFFIES(msec) ((HZ * (msec) + 999) / 1000)
> #define       JIFFIES_TO_MSEC(jiffies) ...
> #endif
> in some kernel-wide header then kill off all the private implementations?

How about this?

#if HZ <= 1000 && !(1000 % HZ)
#define MSEC_TO_JIFFIES(m)      ((1000/HZ)*(m))
#define JIFFIES_TO_MSEC(j)      ((j)/(1000/HZ))
#elif HZ > 1000 && !(HZ % 1000)
#define MSEC_TO_JIFFIES(m)      ((m)/(HZ/1000))
#define JIFFIES_TO_MSEC(j)      ((HZ/1000)*(j))
#else
#define MSEC_TO_JIFFIES(m)      ((HZ*(m) + 999)/1000)
#define JIFFIES_TO_MSEC(j)      ((1000*(j) + HZ - 1)/HZ)
#endif


-- wli

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