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Re: MSEC_TO_JIFFIES is messed up...

To: Ingo Molnar <mingo@xxxxxxx>
Subject: Re: MSEC_TO_JIFFIES is messed up...
From: Valdis.Kletnieks@xxxxxx
Date: Wed, 12 May 2004 17:03:10 -0400
Cc: linux-kernel@xxxxxxxxxxxxxxx, Netdev <netdev@xxxxxxxxxxx>
In-reply-to: Your message of "Wed, 12 May 2004 22:50:28 +0200." <20040512205028.GA18806@elte.hu>
References: <20040512020700.6f6aa61f.akpm@osdl.org> <20040512181903.GG13421@kroah.com> <40A26FFA.4030701@pobox.com> <20040512193349.GA14936@elte.hu> <200405121947.i4CJlJm5029666@turing-police.cc.vt.edu> <Pine.LNX.4.58.0405121255170.11950@bigblue.dev.mdolabs.com> <200405122007.i4CK7GPQ020444@turing-police.cc.vt.edu> <20040512202807.GA16849@elte.hu> <20040512203500.GA17999@elte.hu> <20040512205028.GA18806@elte.hu>
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On Wed, 12 May 2004 22:50:28 +0200, Ingo Molnar said:

> Content-Disposition: attachment; filename="hz-cleanup-2.6.6-A2"
> 
> --- linux/include/linux/time.h.orig   
> +++ linux/include/linux/time.h        
> @@ -177,6 +177,24 @@ struct timezone {
>       (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 
1) - 1)
>  
>  #endif
> +
> +/*
> + * Convert jiffies to milliseconds and back.
> + *
> + * Avoid unnecessary multiplications/divisions in the
> + * two most common HZ cases:
> + */
> +#if HZ == 1000
> +# define JIFFIES_TO_MSECS(x) (x)
> +# define MSECS_TO_JIFFIES(x) (x)
> +#elif HZ == 100
> +# define JIFFIES_TO_MSECS(x) ((x) * 10)
> +# define MSECS_TO_JIFFIES(x) ((x) / 10)
> +#else
> +# define JIFFIES_TO_MSECS(x) ((x) * 1000 / HZ)
> +# define MSECS_TO_JIFFIES(x) ((x) * HZ / 1000)
> +#endif
> +

Looks good to me.. :)

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