Re: Time skew

2009-01-14 Thread Bill Moran 
In response to sc...@centroin.com.br:
 
   I'm facing some strange behavior with an skew in the system clock.
   The hardware is a Dell PowerEdge 2950III, running two instances of 
 FreeBSD 7.0-RELEASE-p5 - amd64 over an ESXi hipervisor.
   To both were allocated 4 processors and 4 GB of RAM, and dmesg for 
 both are identical.
   I'm using clockspeed to synchronize the clock, but just one of 
 them is delaying the clock a lot.

I doubt that clockspeed will ever work for you.  VMWare seems to pause
virtual machines when they're not doing anything in order to allocate
CPU for other running VMs.

   The hardware clock is ok as far as the other virtual machine.
   Where should I start to investigate?

For supported OS (i.e. Windows/Linux) VMWare provides special programs
to keep the clocks in sync.  I expect this is because VMWare knows that
they mangle the clock in such a way that typical clock management
software will never be able to keep it in sync.  One problem is that
most clock synching software assumes that drift is relatively constant
(and clockspeed seems to be the same) but clock drift in a virtual
machine is _anything_ but constant.

Unfortunately, VMWare has no love for FreeBSD.

We've been able to keep clocks in sync by adding a cronjob that runs
ntpdate every minute or so.  Seems draconian, but it gets the job done.

-- 
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/
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RE: Time skew

2009-01-14 Thread Barry Byrne 
 
 -Original Message-
 From: owner-freebsd-questi...@freebsd.org 
 [mailto:owner-freebsd-questi...@freebsd.org] On Behalf Of 
 sc...@centroin.com.br

 Hi All,
 
   I'm facing some strange behavior with an skew in the 
 system clock.
   The hardware is a Dell PowerEdge 2950III, running two 
 instances of 
 FreeBSD 7.0-RELEASE-p5 - amd64 over an ESXi hipervisor.
   To both were allocated 4 processors and 4 GB of RAM, 
 and dmesg for 
 both are identical.
   I'm using clockspeed to synchronize the clock, but just one of 
 them is delaying the clock a lot.
   The hardware clock is ok as far as the other virtual machine.
   Where should I start to investigate?

Marcelo,

I've not used the ESXi hypervisor, but do use ESX 3.5 with FreeBSD, and the
only way I've sucessfully kept FreeBSD servers in time, is to use either
ntpdate or ntpd. Lately, I've found ntpd to be a better solution. Vmware
have a KB article on the best way to configure ntpd on a virtual machine:


http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKCdocType=
kcexternalId=1339sliceId=2docTypeID=DT_KB_1_1dialogID=14730824stateId=0
%200%204678302

For what it's worth this is the ntp.conf I use, which gives me no trouble:

tinker panic 0
restrict 127.0.0.1
restrict default kod nomodify notrap
server time.server.ip

Cheers,

Barry


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Re: Time skew

2009-01-14 Thread Mikel King 

Marcelo,

Try adding either,

hint.apic.0.disabled=1
or
kern.hz=100

to /boot/loader.conf

Reboot the machine and check your time.

The first line is the patch originally noted in the VMWare KB the  
latter is from the FreeBSD handbook on the subject.


Regards,
Mikel

On Jan 14, 2009, at 9:09 AM, sc...@centroin.com.br wrote:


Hi All,

I'm facing some strange behavior with an skew in the system clock.
	The hardware is a Dell PowerEdge 2950III, running two instances of  
FreeBSD 7.0-RELEASE-p5 - amd64 over an ESXi hipervisor.
	To both were allocated 4 processors and 4 GB of RAM, and dmesg for  
both are identical.
	I'm using clockspeed to synchronize the clock, but just one of them  
is delaying the clock a lot.

The hardware clock is ok as far as the other virtual machine.
Where should I start to investigate?

- Marcelo

Dmesg is following:

Copyright (c) 1992-2008 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 is a registered trademark of The FreeBSD Foundation.
FreeBSD 7.0-RELEASE-p5 #0: Mon Nov  3 13:19:30 BRST 2008
   r...@tst.ciplan:/usr/obj/usr/src/sys/TREX-64
Timecounter i8254 frequency 1193182 Hz quality 0
CPU: Intel(R) Xeon(R) CPU   E5410  @ 2.33GHz (2357.36-MHz K8- 
class CPU)

 Origin = GenuineIntel  Id = 0x10678  Stepping = 8

Features 
=0xfebfbffFPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CM

OV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS
 Features2=0x82201SSE3,SSSE3,CX16,b19
 AMD Features=0x20100800SYSCALL,NX,LM
 AMD Features2=0x1LAHF
usable memory = 4013707264 (3827 MB)
avail memory  = 3883839488 (3703 MB)
ACPI APIC Table: PTLTD  APIC  
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
cpu0 (BSP): APIC ID:  0
cpu1 (AP): APIC ID:  1
cpu2 (AP): APIC ID:  2
cpu3 (AP): APIC ID:  3
MADT: Forcing active-low polarity and level trigger for SCI
ioapic0 Version 1.1 irqs 0-23 on motherboard
kbd1 at kbdmux0
ath_hal: 0.9.20.3 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413,  
RF5413)

hptrr: HPT RocketRAID controller driver v1.1 (Nov  3 2008 13:19:19)
acpi0: PTLTD   RSDT on motherboard
acpi0: [ITHREAD]
acpi0: Power Button (fixed)
Timecounter ACPI-safe frequency 3579545 Hz quality 850
acpi_timer0: 24-bit timer at 3.579545MHz port 0x1008-0x100b on acpi0
cpu0: ACPI CPU on acpi0
acpi_throttle0: ACPI CPU Throttling on cpu0
cpu1: ACPI CPU on acpi0
acpi_throttle1: ACPI CPU Throttling on cpu1
acpi_throttle1: failed to attach P_CNT
device_attach: acpi_throttle1 attach returned 6
cpu2: ACPI CPU on acpi0
acpi_throttle2: ACPI CPU Throttling on cpu2
acpi_throttle2: failed to attach P_CNT
device_attach: acpi_throttle2 attach returned 6
cpu3: ACPI CPU on acpi0
acpi_throttle3: ACPI CPU Throttling on cpu3
acpi_throttle3: failed to attach P_CNT
device_attach: acpi_throttle3 attach returned 6

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