Date: Thu, 08 Jul 1999 18:40:23 +0900 From: Seigo Tanimura <tanimura@naklab.dnj.ynu.ac.jp> To: dfr@nlsystems.com Cc: Seigo Tanimura <tanimura@naklab.dnj.ynu.ac.jp> Subject: Re: Rewriting pca(4) using finetimer(9) (was: Re: MPU401 now worksunder New Midi Driver Framework with a Fine Timer) Message-ID: <199907080940.SAA26649@rina.naklab.dnj.ynu.ac.jp> In-Reply-To: Your message of "Thu, 8 Jul 1999 09:54:42 %2B0100 (BST)" References: <Pine.BSF.4.10.9907080952480.558-100000@salmon.nlsystems.com>
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On Thu, 8 Jul 1999 09:54:42 +0100 (BST), Doug Rabson <dfr@nlsystems.com> said: dfr> If I understand this correctly, you are suggesting that we program timer0 dfr> so that we only take interrupts when a finetimer is due to fire? If so, dfr> then it sounds very good. The idea of taking 6000+ interrupts/sec made me dfr> uneasy, even though most would return without doing any work. Yes, that is what I am doing now. And some further discussion... > t' > \sum_(k=0)^(j) dt_rem(c_k) > > where the right hand side of the inequality is the time span after which > the callout c_k is made. Then c' is inserted after c_j and new dt_rem(c_(j+1)) > and dt_rem(c_(j+2)) are determined. Now we can acquire_timer0() with dt_rem(c_0). If t' is less than dt_rem(c_0) then we have no feasible j. This is the case in which we must reaquire_timer0() using t'. Then, after interting c', dt_rem(c_1) is updated to be (dt_rem(c_1) - (time elapsed since the last aquire_timer0())), so that c_1 can be armed later. There is one problem in this method. acquire_timer0() is only implemented for i386. We would need to write something equivalent for alpha... Seigo Tanimura <tanimura@naklab.dnj.ynu.ac.jp> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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