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Re: [MIPS] Use generic NTP code for all MIPS platforms

To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Subject: Re: [MIPS] Use generic NTP code for all MIPS platforms
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Tue, 14 Aug 2007 16:26:13 +0100 (BST)
Cc: vagabon.xyz@gmail.com, linux-mips@linux-mips.org
In-reply-to: <20070814.231255.74753150.anemo@mba.ocn.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <46C07F36.1070308@gmail.com> <20070814.020229.29578157.anemo@mba.ocn.ne.jp> <46C0A83B.2090003@gmail.com> <20070814.231255.74753150.anemo@mba.ocn.ne.jp>
Sender: linux-mips-bounce@linux-mips.org
On Tue, 14 Aug 2007, Atsushi Nemoto wrote:

> Some difficulties are:
> 
> * timekeeping subsystem calls {read,update}_persistent_clock() with
>   irq-disabled.  But most RTC class routines might sleep.
> 
> * RTC class can have multiple RTCs on the system.
> 
> * There are already some conflicting features in RTC class ---
>   rtc_suspend and rtc_resume try to adjust the wall clock.
> 
> * IIRC Some people said "NTP sync can be done all in userland" ;-)

 NTP sync in the kernel disturbs the timer interrupt with some setups, 
affecting the dispersion and thus the quality of timekeeping horribly.

  Maciej

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