Date: Tue, 30 Mar 2010 19:43:46 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hackers@freebsd.org, =?UTF-8?B?RGFnLUVybGluZyBTbcO4cmdyYXY=?= <des@des.no> Subject: Re: periodically save current time to time-of-day hardware Message-ID: <4BB22A42.7050003@icyb.net.ua> In-Reply-To: <201003291044.28544.jhb@freebsd.org> References: <4BACC791.70502@icyb.net.ua> <20100327214634.GI32799@server.vk2pj.dyndns.org> <86fx3k7jqi.fsf@ds4.des.no> <201003291044.28544.jhb@freebsd.org>
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on 29/03/2010 17:44 John Baldwin said the following: > On Sunday 28 March 2010 7:45:25 am Dag-Erling Smørgrav wrote: >> Peter Jeremy <peterjeremy@acm.org> writes: >>> A new kthread which sleeps on channel "update_rtc". When woken, it >>> checks to see if it's within (say) 50msec of a second boundary and so, >>> it does a trylock on the (new) RTC mutex. If it grabs the mutex then >>> it performs the update. If it was too far from the second boundary or >>> it fails to grab the mutex then it sleeps until the next second >>> boundary and tries again. >>> >>> The existing resettodr() would then turn into a wakeup(update_rtc). >> Sounds good to me, but if only that thread has access to the RTC, why >> bother with a mutex? > > I would dispense with the kthread and just use a callout (or have a callout > schedule a task for taskqueue_thread). Guys, do you think that periodic saving of system clock to hardware and making resettodr asynchronous are dependent issues? Or are they orthogonal and can be implemented independently? -- Andriy Gapon
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