Date: Fri, 21 Aug 1998 11:10:23 -0700 (PDT) From: David Wolfskill <dhw@whistle.com> To: freebsd-hackers@FreeBSD.ORG, rkw@Dataplex.NET Subject: Re: proposal to not change time_t Message-ID: <199808211810.LAA05293@pau-amma.whistle.com> In-Reply-To: <l03130300b203323fc2e9@[208.2.87.13]>
next in thread | previous in thread | raw e-mail | index | archive | help
>Date: Fri, 21 Aug 1998 09:35:51 -0500 >From: Richard Wackerbarth <rkw@Dataplex.NET> >You are correct that time precision, by itself, will never solve the >multi-processor race condition that you describe. >Rather than use the completion time of the operation, we should be using >the starting time. This, coupled with the requirement, in "make" that >the result always be "newer", by at least one tick, than each of its >inputs will cause the results to be correct. I would expect that if you're concerned with timestamps generated by multi-processing systems, that it might be worth considering using a CPU number as the last few bits of the timestamp -- beyond the accuracy of anything "real" -- as a tie-breaker. As I recall, this is the technique IBM used on the s/3x0 "store clock" instruction.... david -- David Wolfskill UNIX System Administrator dhw@whistle.com voice: (650) 577-7158 pager: (650) 371-4621 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199808211810.LAA05293>