Bug 6497 - timer at double of normal speed
Summary: timer at double of normal speed
Alias: None
Product: Timers
Classification: Unclassified
Component: Realtime Clock (show other bugs)
Hardware: i386 Linux
: P2 normal
Assignee: timers_realtime-clock
Depends on:
Reported: 2006-05-05 09:58 UTC by Marijn Schouten
Modified: 2006-05-18 07:48 UTC (History)
3 users (show)

See Also:
Kernel Version:
Regression: ---
Bisected commit-id:


Description Marijn Schouten 2006-05-05 09:58:32 UTC
forked from http://bugzilla.kernel.org/show_bug.cgi?id=3927 per Andi Kleen's 

Most recent kernel where this bug did not occur: none
Distribution: Gentoo
Hardware Environment: Athlon64 3200+ MSI RS482M4 (Ati rs482 and sb450)
Software Environment: bash/date
Problem Description: the timer runs twice as fast as expected, looking at your 
watch and running date for two consecutive seconds produces a time difference 
of two seconds instead of only one.

Steps to reproduce: boot kernel without noapic, login, run date with one second 
intervals. Watch it report dates with 2 second intervals.
Workaround: boot with noapic
Comment 1 Marijn Schouten 2006-05-07 05:58:38 UTC
The previous situation is with ACPI disabled in BIOS. If I enable ACPI in BIOS 
and try to boot without noapic then I get the following kernel panic:
not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
Comment 2 Marijn Schouten 2006-05-07 09:37:57 UTC
I've checked back to version 2.6.12 but none completely boot with ACPI enabled.  
Comment 3 Marijn Schouten 2006-05-18 07:48:30 UTC
I was able to get ACPI working (see 
http://bugzilla.kernel.org/show_bug.cgi?id=6522) and this has allowed me to 
remove the noapic option without getting a double speed timer.

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