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Re: [Xen-users] Re: Windows and Multiple CPUS?

from [Andrew Lyon] [Permanent Link][Original]
To: "Nemeth, Tamas" <nice@xxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] Re: Windows and Multiple CPUS?
From: "Andrew Lyon" <andrew.lyon@xxxxxxxxx>
Date: Fri, 19 Sep 2008 17:18:32 +0100
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
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I have noticed the same thing, does it cause other problems?

Here are logs from different versions of windows pinging the default
gateway and localhost, note that when the time is irregular the
response happens instantly or too quickly to be correct timing,  i.e.
multiple response lines are printed at once or very close together,
much quicker than the stated time, only when the time is sensible does
each line appear with regular timing:

XP Pro 32 Bit 2 cpus:

C:\Documents and Settings\Administrator>ping 10.0.4.1 -t

Pinging 10.0.4.1 with 32 bytes of data:

Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time=6140ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64

and localhost:

C:\Documents and Settings\Administrator>ping -t localhost

Pinging localhost [127.0.0.1] with 32 bytes of data:

Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6186ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-6187ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128

If you set the affinity of the ping.exe process to a single CPU
sometimes the problem goes away, I think the time is not sync over the
cpus and so the ping timings over/under flow and give strange values?
or the time is taken from one cpu and by chance when I set the
affinity to the cpu that has the master timer and the ping works
properly?

Windows 2003 32 bit Standard Edition 4 cpus:

C:\Documents and Settings\Administrator>ping -t 10.0.4.1

Pinging 10.0.4.1 with 32 bytes of data:

Reply from 10.0.4.1: bytes=32 time=2434ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-501ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-604ms TTL=64
Reply from 10.0.4.1: bytes=32 time=2434ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-501ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time=2434ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-501ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time=2434ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-501ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-501ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-604ms TTL=64
Reply from 10.0.4.1: bytes=32 time=2434ms TTL=64
Reply from 10.0.4.1: bytes=32 time=-501ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64

C:\Documents and Settings\Administrator>ping -t localhost

Pinging xen-win2003x86 [127.0.0.1] with 32 bytes of data:

Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-2436ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128
Reply from 127.0.0.1: bytes=32 time=501ms TTL=128

Each time I run the ping I get a different response time:

Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128
Reply from 127.0.0.1: bytes=32 time=-605ms TTL=128



Windows 2008 Enterprise Edition 32 bit with 8 CPUs seems to not have
the problem:

C:\Users\Administrator>ping -t 10.0.4.1

Pinging 10.0.4.1 with 32 bytes of data:
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64
Reply from 10.0.4.1: bytes=32 time<1ms TTL=64

C:\Users\Administrator>ping -t localhost

Pinging WIN-PA2NTBT8TNB [::1] from ::1 with 32 bytes of data:
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms


Andy

On Fri, Sep 19, 2008 at 4:15 PM, Nemeth, Tamas <nice@xxxxxxxxxxxxxxx> wrote:
> Hi,
>
> I've tried to run w2k3 server with multiple CPUs, but i had to realize
> that a HVM virtualized w2k3 has some timing (clock) issues. Timing
> becomes somehow imprecise. I tried it on 64bit hypervisor and 32bit
> dom0, xen version 3.2.1. I tried to ping a host from a multiple VCPU
> windows and the packets coming back seemed to arrive earlier then they
> left the NIC, or something like this. Can you confirm this symtom?
> (However it's possible, this is a problem of networking, not timing.)
> This problem doesn't exist on single VCPU Windows HVM domUs.
>
> Cheers
>
> Tamas
>
>
> 2008. 09. 19, péntek keltezéssel 14.46-kor Andrew Lyon ezt írta:
>> On Fri, Sep 19, 2008 at 2:39 PM, Andrew Lyon <andrew.lyon@xxxxxxxxx> wrote:
>> > Hi,
>> >
>> > Am I correct in thinking that when Xen is running on a multi-core /
>> > smp system and several cpus are assigned to a VM they are "presented"
>> > as multiple single core cpus rather than 1 or more multi-core cpus?
>> >
>> > Microsoft CPU limits are for physical sockets, not cores.
>> >
>> > Windows XP and Vista are limited to two physical cpus, running under
>> > Xen the maximum cpus I have seen in task manager and system properties
>> > is 2, although device manager shows all of the assigned cpus (up to
>> > 8).
>> >
>> > Windows 2003 and 2008 standard edition are limited to 4 cpus, which is
>> > the limit I find under Xen, again device manager shows all assigned
>> > cpus (up to 8).
>> >
>> > Is there any way to make windows see the cpus as multi-core so that
>> > all 8 cores can be used ?
>> >
>> > Andy
>> >
>>
>> I've also noticed that if I run "xm list" repeatedly as the VM is
>> starting up I can actually see the cpus being initialized, the value
>> matches the limit i find in windows:
>>
>> A Windows 2003 R2 Standard Edition 32 Bit VM:
>>
>> #grep vcpu Win2003x86.cfg
>> vcpus=8
>>
>> xm list (several times during boot process)
>>
>> Win2003x86                                  24  2048     1
>> Win2003x86                                  24  2048     2
>> Win2003x86                                  24  2048     3
>> Win2003x86                                  24  2048     4
>>
>> But if i booted this version of windows on the raw hardware all 8 cpus
>> would be utilized.
>>
>> Andy
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-users
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
>

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