Re: Timekeeping hosed by factor 3, high lapic[01] interrupt rates

From: Jens Schweikhardt <schweikh_at_schweikhardt.net>
Date: Thu, 26 May 2005 22:58:31 +0200
On Thu, May 26, 2005 at 10:30:16AM -0700, Doug White wrote:
# On Mon, 23 May 2005, Jens Schweikhardt wrote:
# 
# > ...
# > # # 3. Backout rev 1.218 of src/sys/i386/isa/clock.c so the irq0 interrupt
# > # # handler is reactivated and the RTC fiddled.
# > #
# > # Will do so next. I've nailed the change between March 6 and March 30.
# > # 1.218 is from 2005/03/24 21:34:16, which would fit.
# >
# > We have a winner. Backing out 1.218 from a 2005/03/24 system does the trick,
# > as well as a CURRENT without 1.218 (but 1.219-220 in there) bring back irq0
# > and time dilation is gone. All clocks work correctly.
# 
# Hm ... not sure what part of that commit is the bad part.  You might try
# changing
# 
# if (!using_lapic_timer) {
# 
# to
# 
# if(1) {
# 
# in the most recent rev of clock.c to register irq0 again.  If that doesn't
# chang ethe dialation then something else in the system must be depending
# on the RTC periodic interrupt.

It does make time dilation go away.

# > Now the question is: what is so special in my system so that I appear
# > to be the only one to notice the problem?
# 
# Good question. What CPUs do you have in that machine again? Copy out the
# 'CPU' and related lines from dmesg.

One P4 Prescott, with HT enabled,

Copyright (c) 1992-2005 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
	The Regents of the University of California. All rights reserved.
FreeBSD 6.0-CURRENT #0: Mon May 23 22:38:19 CEST 2005
    toor_at_hal9000.schweikhardt.net:/share/HEAD/obj/share/HEAD/src/sys/HAL9000
MPTable: <OEM00000 PROD00000000>
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (2994.90-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf33  Stepping = 3
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x41d<SSE3,RSVD2>,MON,DS_CPL,CNTX-ID>
  Hyperthreading: 2 logical CPUs
real memory  = 1072627712 (1022 MB)
avail memory = 1040846848 (992 MB)
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
ioapic0: Changing APIC ID to 2
ioapic0: Assuming intbase of 0
ioapic1: Assuming intbase of 24
ioapic0 <Version 2.0> irqs 0-23 on motherboard
ioapic1 <Version 2.0> irqs 24-47 on motherboard
[...]

Regards,

	Jens
-- 
Jens Schweikhardt http://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)
Received on Thu May 26 2005 - 18:58:45 UTC

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