From owner-freebsd-current  Tue Nov 17 05:44:44 1998
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To: Poul-Henning Kamp <phk@critter.freebsd.dk>
cc: Kevin Day <toasty@home.dragondata.com>, current@FreeBSD.ORG,
        yokota@zodiac.mech.utsunomiya-u.ac.jp
Subject: Re: MediaGX and calcru: negative time 
In-reply-to: Your message of "Tue, 17 Nov 1998 09:52:42 +0100."
             <26036.911292762@critter.freebsd.dk> 
References: <26036.911292762@critter.freebsd.dk> 
Date: Tue, 17 Nov 1998 22:38:35 +0900
From: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp>
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>>> FreeBSD 2.2.7-RELEASE #0: Wed Oct 21 16:22:35 CDT 1998
>>>     devel@kevin1.touchmaster:/usr/src/sys/compile/DEVEL
>>> CPU: Cyrix GXm (0.00-MHz 586-class CPU)
>>>   Origin = "CyrixInstead"  Id = 0x540  DIR=0x3346  Stepping=3  Revision=3
>>> real memory  = 63963136 (62464K bytes)
>>> avail memory = 60252160 (58840K bytes)
>>
>>FreeBSD 3.0-RELEASE #0: Mon Nov 16 16:10:02 CST 1998
>>    root@kevin1.touchmaster:/usr/src/sys/compile/DEVEL
>>Timecounter "i8254"  frequency 1193182 Hz  cost 40336 ns
>>Timecounter "TSC"  frequency 20172892 Hz  cost 180 ns
>>CPU: Cyrix GXm (20.17-MHz 586-class CPU)
>>  Origin = "CyrixInstead"  Id = 0x540  Stepping=0  DIR=0x3346
>>  Features=0x808131<FPU,TSC,MSR,CX8,CMOV,MMX>
>>real memory  = 63963136 (62464K bytes)
>>avail memory = 60243968 (58832K bytes)
>
>>According to date, i'm running about 15-30x the speed I should be.
>>
>>Has anyone else reported this for a GXm?
>
>This is because the speed of your TSC counter is WAY wrong.
>
>If you know what frequency it should be,
>	sysctl -w kern.timecounter.frequency=XXXXXX
>where XXXXXX is that frequency in Hz.
>
>Even better yet, try to find out why the frequency is so wrong
>in sys/isa/clock.c

The probelem report kern/6630 "[PATCH] Fix for Cyrix I8254 bug" has a
possible explanation and a patch.  I have heard from a couple of users
that while the patch does not completely eradicate the problem, it
makes things much better.

Kazu

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