RE: [Xen-devel] Question about machine time delay in guest domains(Full virtualization)

["You, Yongkang" <yongkang.you@xxxxxxxxx>]

Hi Christi,

 

I can reproduce the time delay by just one x86_64 rhel5u1 guest under specjbb2005, although the delay is not so great like your data. I found it would be slow 100 secs, after running specjbb2005 2000 secs. I also tried timer_mode=1 or 2. They all met time slow issue.

 

BTW, I only catch this issue on x86_64 RHEL5u1 guest. With more guests running, the guest timer would be slower. But x86_32 RHEL5u1 guest doesn't meet this issue. And without workload, guest timer is acceptable.

 

Best Regards,

Yongkang You

 

---

From: christie kumiko goto [mailto:christie0123@xxxxxxxxx]
Sent: Wednesday, January 09, 2008 8:33 PM
To: You, Yongkang
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Question about machine time delay in guest domains(Full virtualization)

Hi, Yongkang,

Thanks so much!!

> Did you try if only 
creating 1 domains with 2 cpus?

I did the following 2 patterns.
  
1) 2 domains with 2 vcpus (each domain shares 2 physical cpus)
  2) 4 
domains with 2 vcpus (each domain shares 2 physical cpus) 

>What's 
your platform and guest OS version?

Could you see the following 
info?

platform: x86_64
OS: RHEL5u1 2.6.18 (details are 
below)

--------------------
#uname -a
Linux DL360-dom0-RHEL5u1 
2.6.18-53.el5xen #1 SMP Wed Oct 10 16:48:44 EDT 
2007 x86_64 x86_64 x86_64 
GNU/Linux

# xm info
host : DL360-dom0-RHEL5u1
release : 
2.6.18-53.el5xen
version : #1 SMP Wed Oct 10 16:48:44 EDT 2007
machine : 
x86_64 
nr_cpus : 2
nr_nodes : 1
sockets_per_node : 
1
cores_per_socket : 2
threads_per_core : 1
cpu_mhz : 1866
hw_caps : 
bfebfbff:20000800:00000000:00000140:0004e3bd:00000000:00000001
total_memory : 
16381 
free_memory : 1
xen_major : 3
xen_minor : 1
xen_extra : 
.0-53.el5
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p 
hvm-3.0-x86_64
xen_pagesize : 4096
platform_params : 
virt_start=0xffff800000000000 
xen_changeset : unavailable
cc_compiler : 
gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)
cc_compile_by : 
brewbuilder
cc_compile_domain : build.redhat.com
cc_compile_date : Wed Oct 
10 16:30:57 EDT 2007 
xend_config_format : 2

# cat 
/proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 
6
model : 15
model name : Intel(R) Xeon(R) CPU E5320 @ 1.86GHz
stepping 
: 7
cpu MHz : 1866.730 
cache size : 4096 KB
physical id : 
0
siblings : 1
core id : 0
cpu cores : 1
fpu : yes
fpu_exception 
: yes
cpuid level : 10
wp : yes
flags : fpu tsc msr pae mce cx8 apic 
mtrr mca cmov pat pse36 clflush dts 
acpi mmx fxsr sse sse2 ss ht tm syscall 
lm constant_tsc pni monitor 
ds_cpl vmx est tm2 cx16 xtpr lahf_lm
bogomips 
: 4669.03
clflush size : 64
cache_alignment : 64
address sizes : 36 
bits physical, 48 bits virtual 
power management:

processor : 
1
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : 
Intel(R) Xeon(R) CPU E5320 @ 1.86GHz
stepping : 7
cpu MHz : 
1866.730
cache size : 4096 KB
physical id : 1
siblings : 1
core id : 
0
cpu cores : 1
fpu : yes
fpu_exception : yes
cpuid level : 10
wp 
: yes
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush 
dts 
acpi mmx fxsr sse sse2 ss ht tm syscall lm constant_tsc pni monitor 
ds_cpl vmx est tm2 cx16 xtpr lahf_lm
bogomips : 4669.03
clflush size : 
64
cache_alignment : 64
address sizes : 36 bits physical, 48 bits 
virtual
power management:

-------------------------

Thanks 
again,
I really appreciate your kind help!
;)

-Christi

2008/1/9, You, Yongkang <yongkang.you@xxxxxxxxx>:

On Tuesday, January 08, 2008 10:03 PM christie kumiko goto wrote:

> ------------------------------------------------------
> <<Environment>>
> -Host machine has 2 cores (core number 0-1)
> -Guest OSs: Full virtualization
>
> *test 1
> 4 domains share 2 core (each domain has 2 vcpu)
> ->result: actual test time : test time measured in guest domains = 4:1
>
> *test 2
> 2 domains share 1 core and the other 2 domains share the other 1 core.
> ->result: actual test time : test time measured in guest domains = 2:1
> ------------------------------------------------------

Hi Christi,

Did you try if only creating 1 domains with 2 cpus?
What's your platform and guest OS version? There are some new configurations for guest timer, such as timer_mode=1/2/3 (default timer mode is 0). You can set it in the guest config file. For some new OS, we can use timer_mode=1/2 to make the timer more acccurate. But I am not sure if they can work in your testing.

Best Regards,
Yongkang You

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