kern/79339: [patch] Kernel time code sync with improvements from DragonFly

[Uwe Doering]

Joshua Coombs wrote:
> The following reply was made to PR kern/79339; it has been noted by GNATS.
> 
> From: "Joshua Coombs" <jcoombs at gwi.net>
> To: <freebsd-gnats-submit at FreeBSD.org>,
> 	"Joshua Coombs" <jcoombs at gwi.net>
> Cc:  
> Subject: Re: kern/79339: [patch] Kernel time code sync with improvements from DragonFly
> Date: Wed, 30 Mar 2005 09:33:59 -0500
> 
>  Testing with wakeup_latency.c on a 5.3-Rel box shows the same symptom set. 
>  I've not yet tested the proposed fix on 5-x.  I will try dupilcating this 
>  issue on 6-current as well to nail down the problem scope. 

Please also look at what's actually in DragonFly's CVS repository.  Your 
PR is based on the original patch, while the code in DragonFly is more 
sophisticated.  Namely, tvtohz() was split into two functions, 
tvtohz_low() and tvtohz_high(), which replace the original function 
depending on the context tvtohz() appears in.

 From this I conclude that the original patch is insufficient (likely to 
break parts of the kernel), and that integrating this improvement into 
FreeBSD might not be as easy and straightforward as it appears to be at 
first glance.  On the other hand, with some effort it ought to be doable.

    Uwe
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