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SubjectRe: gettimeofday non-monotonic on 2.2.7 SMP
 =>From: Simon Kirby <sim@netnation.com>
=>...
=>My dual celeron 300As @ 450 MHz (2.2.9) running your program gives:
=>
=>Mon May 17 18:05:40 1999: fwd:774496/0:back max 0000000
=>Mon May 17 18:05:41 1999: fwd:913473/0:back max 0000000

That's what I expect, but what I get is:

Mon May 17 18:57:17 1999: fwd:362637/4:back max 0000003
Mon May 17 18:57:18 1999: fwd:866801/9:back max 0000003
Mon May 17 18:57:19 1999: fwd:873531/7:back max 0000004
Mon May 17 18:57:20 1999: fwd:872292/8:back max 0000003
Mon May 17 18:57:21 1999: fwd:873949/9:back max 0000003

with max [i.e. maximum clock decrement detected] going up to
5000-10000 (5-10ms) when I'm writing a CD or scrolling a Netscape
window.

Somebody else also reported success with a Dell SMP box running 2.2.9,
so I compiled a copy for myself, but it didn't make any difference
from 2.2.7.

=>Another thing..Perhaps try enabling "MTRR" in the kernel if it's not
=>already to synchronize TSCs at bootup. I'm not sure if MTRR does this or
=>not, actually, so maybe try flashing a new BIOS if all else fails. I know
=>some BIOSes don't synchronize the TSCs properly, and this would confuse
=>gettimeofday()...

I'm using MTRR, but that code doesn't mention the TSC. My box is an
Intel N440BX motherboard with the latest BIOS; what are your Celerons
on?

Thanks for trying the program!

d.

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