Date: Mon, 29 Mar 2010 10:44:28 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Dag-Erling =?utf-8?q?Sm=C3=B8rgrav?= <des@des.no>, Andriy Gapon <avg@icyb.net.ua> Subject: Re: periodically save current time to time-of-day hardware Message-ID: <201003291044.28544.jhb@freebsd.org> In-Reply-To: <86fx3k7jqi.fsf@ds4.des.no> References: <4BACC791.70502@icyb.net.ua> <20100327214634.GI32799@server.vk2pj.dyndns.org> <86fx3k7jqi.fsf@ds4.des.no>
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On Sunday 28 March 2010 7:45:25 am Dag-Erling Sm=C3=B8rgrav 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). >=20 > 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= =20 schedule a task for taskqueue_thread). =2D-=20 John Baldwin
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