In message <[EMAIL PROTECTED]>, David Malone writes: >> I'm not sure I know what you mean by "trivial timecounter", but the >> only reason we don't have a way to deregister a timecounter yet is >> that so far I'm probably the only one who have ever need it :-) > >I was thinking about this recently too actually, as I was going to >see how good the 64 bit counter on ath cards was in comparison to >other things that were available.
The first gottcha to look out for is upper/lower half rollover issues, if you read it as two 32 bit registers: you need to check if the lower part rolled over without the upper part getting updated, or the more pathological case: the upper part being updated before the lower part rolled voer. 32 bits is quite likely to be enough for a timecounter so that may not even be an issue. Next is the matter of the crystal that drives it, the temperature stability of that xtal etc etc. >other things that were available. I'm not sure how much complexity >a timecounter that could vanish at any moment would introduce - I >didn't get that far yet. It's not too bad, we can switch pretty quickly. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ cvs-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/cvs-all To unsubscribe, send any mail to "[EMAIL PROTECTED]"
