Date: Sat, 13 Apr 2002 16:20:41 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: John Hay <jhay@icomtek.csir.co.za> Cc: hackers@freebsd.org Subject: Re: microtime trustworthiness during booting? Message-ID: <19993.1018707641@critter.freebsd.dk> In-Reply-To: Your message of "Sat, 13 Apr 2002 15:50:10 %2B0200." <200204131350.g3DDoBn69302@zibbi.icomtek.csir.co.za>
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In message <200204131350.g3DDoBn69302@zibbi.icomtek.csir.co.za>, John Hay write s: >Hi, > >>From what stage during the boot process can I trust that microtime() will >give me incrementing time? > >The reason I ask is that I see microtime() jump backwards consistently >during the ich_calibrate() function in the ich sound driver. The values >look basically the same every time. Something like this: > >t1 2 sec 389291 usec >t2 0 sec 32061 usec Until interrupts work you cannot rely on timecounters. You should probably use microuptime() not microtime() any case. >Can it be that there is some kind of glitch somewhere when the TSC >take over as timecounter? Unlikely. -- 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-hackers" in the body of the message
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