Date: Mon, 18 Feb 2002 07:25:50 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Bruce Evans <bde@zeta.org.au> Cc: Terry Lambert <tlambert2@mindspring.com>, Matthew Dillon <dillon@apollo.backplane.com>, Julian Elischer <julian@elischer.org>, Alfred Perlstein <bright@mu.org>, arch@FreeBSD.ORG, jhb@FreeBSD.ORG, peter@wemm.org, jake@locore.ca Subject: Re: gettimeofday() and crhold()/crfree() (was Re: gettimeofday()andcopyout(). Is copyout() MPSAFE on non-i386 archs? ) Message-ID: <33058.1014013550@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 18 Feb 2002 14:52:51 %2B1100." <20020218144148.F4583-100000@gamplex.bde.org>
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In message <20020218144148.F4583-100000@gamplex.bde.org>, Bruce Evans writes: >> I *know* that it is a significant win to flip-flop the >> timecounter context into a reflected user space page >> on each and every clock interrupt. > >That can't be used to implement gettimeofday(). It can only be used >to implement the userland equivalants of get_micro[up]time() and >get_nano[up]time(). I don't like using these even for stamping file >times in seconds in the kernel (though they have more than enough >precision for this), since they give times that are incoherent >relative to other ways of determining the time. Erhm... I am going to ask to let this this discussion die out now, nobody seems to have entirely grasped the idea so I think we shall postpone it until I have some patches. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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