On Thu, 8 Jul 1999 09:54:42 +0100 (BST), Doug Rabson <d...@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. I have been reading the i8254 data sheet for another couple of days, to find a new problem. If we have a callout to be made before the timer fires, the counter needs to be reprogrammed with a new value. We cannot reload the new counter value immediately; an i8254 does not load the new value until the currrent period finishes (ie the timer fires) or the gate rises. Thus a callout will have an average delay of 0.5/hz = 50ms. This is too long for a timeout in microseconds. Seigo Tanimura <tanim...@naklab.dnj.ynu.ac.jp> To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-hackers" in the body of the message
